Roast Boneless Leg of Lamb
How to Roast a Boneless Leg of Lamb
Nothing could be easier than roasting a boneless leg of lamb for dinner. Growing up, I remember Sunday dinners of roast leg lamb served with roasted potatoes and mint jelly and eating the leftovers during the week. We roasted a lamb this week for dinner, had leftovers the next night and I’ve been making sandwiches for the last couple of days.
Buying a Leg of Lamb
There are basically three ways you can buy a leg of lamb and each has its advantages. There are actually more than these three cuts, but for simplicity, let’s go with three. By the way, even though a lamb has 4 legs, only the 2 back legs are referred to as “leg of lamb”.
Bone-in leg of lamb is usually a little cheaper, cooks faster than boneless, gives you a bone for making stock for lamb stew and because of the bone is a little juicier and has more flavor. A domestic leg of lamb weighs about 7 to 8 pounds.
Boneless leg of lamb with the bones removed is perfect for roasting and easy to carve. You can find it at your supermarket with the thin membrane (called fell) removed and the meat wrapped in a net to hold it together and keep its form.
Whether you buy the whole leg and have it boned or just the top half (sirloin half) or bottom half (shank half) really depends on how many you are serving and your personal preferences.
The sirloin half (consisting of the top of the leg and part of the hip) is meatier and more tender than the shank half (consisting of the lower part of the leg) which is chewier because it has more connective tissue. However, cooked properly, the connective tissue breaks down to be more tender and gelatinous with lots of flavor.
Butterflied leg of lamb is just a boneless leg that has been cut down the center in half but not completely through. The halves are opened to lay flat making the meat easier to grill or broil but can also be stuffed and rolled.
American (Domestic), New Zealand or Australian Lamb?
I will start off by quoting The Complete Meat Cookbook by Bruce Aidells and Denis Kelly, “When it comes to flavor, tenderness, and overall quality, you can’t beat lamb from the United States, especially California, Colorado, and Vermont”
No matter what country you buy it from, try to get it fresh. A lot of the lamb coming over from Australia and New Zealand is frozen although more and more is coming over fresh. You will find the New Zealand and Australian lamb to be smaller in size and weighing less.
One of the big differences between American lamb and “Down Under” lamb is diet. While the New Zealand and Australian lamb are raised almost exclusively on grass, American lamb is “finished” on a grain, which may be the reason the meat is a bit milder.
Roasting Technique
I said roasting a leg of lamb is simple but first you have to decide what method of roasting you want to follow. Everyone has his or her own ideas on roasting meat these days. If you follow Barbara Kafka’s technique as described in her informative Roasting – A Simple Art, you start at 500ºF for 10 minutes, then lower heat to 425º until the meat is at the desired temperature.
If you are a fan of Bruce Aidell and Denis Kelly in their Complete Meat Cookbook, you might roast the lamb at 350ºF the entire time until desired temperature.
Me, I like both these methods but I’m also a fan of Julee Rosso & Sheila Lukins’ The New Basics Cookbook. I broke my teeth on this book when I first started learning how to cook and go back to it often as a reference. I think it is one of the most important cookbooks you can own when starting out.
They give you all sorts of choices; bone in, bone out, high-heat, low-heat, stuffed, not stuffed but we went with starting at 450ºF for 30 minutes and then reducing the heat to 375ºF until our desired internal temperature.
You really can’t go just by time because there are so many factors that can effect the eventual temperature including the weight of the meat you are cooking, how tightly it is tied, is it stuffed or not, how hot your oven is really cooking at, how long you let it rest - that kind of stuff.
What is the desired internal temperature?
Lamb is naturally tender so you don’t want to over-cook it. Most chefs will tell you to cook and serve it rare. In our house, we like it more medium especially when serving it to the kids. If I was serving the lamb to guests who like it rare, I might pull it out rare, cut off a piece of the meat and continue cooking the rest for a few more minutes until medium. The question is what temperature is rare, medium-rare and medium?
If you look through 10 different cookbooks, you may find 10 different temperature ranges for each level of doneness. For example, The Complete Meat Cookbook says rare is 125ºF to 130ºF, medium-rare at 130ºF to 140ºF, and medium at 140ºF to 150ºF.
The New Basics Cookbook sees rare at 135ºF to 140ºF and medium at 150ºF to 155ºF.
And then there is the USDA Recommendation. They see rare at 140ºF, medium-rare at 150ºF, and medium at 160ºF. Most chefs would tell you an internal temperature at 160 is well done and too dry.
The answer is to experiment and figure out what temperature is best for you. Once you know that, you can cook it anyway you want knowing just when to remove it from the oven.
Resting & Thermometers
A mistake many home cooks make and certainly affects the final temperature is resting time. As with all roasts, you want to remove them about 5 degrees before they reach the desired ideal internal temperature. This is to allow the juices to redistribute throughout the entire piece of meat.
As the meat rests, it will continue to cook about 5 more degrees, the juices will redistribute and you will end up with a more flavorful, tender result. Never remove the meat from the oven and start carving. Give it a short and meaningful rest.
As for thermometers, they are not all alike and if you have an old meat thermometer that has been in your kitchen drawer for years, it may need to be recalibrated or thrown out and replaced.
We used our old meat thermometer and pulled the meat out at our desired temperature of 140ºF and then tested it with an instant thermometer to see that it read 150ºF. After resting, it ended up at about 155ºF and was ok for us, but you can see how important it is that your thermometer is accurate. Then again, maybe my old thermometer was really the accurate one. I’ll have to test them in boiling water.
Roast Boneless Leg of Lamb
You really don’t have to do too much to have good results with a boneless leg of lamb. We added some herbs to it but you could just season it with salt and pepper like my mother did and have a great outcome.
We used the pan juices, along with some of the herbs that fell off when removing the netting and a cup of demi glace to make an incredible pan sauce that even the kids raved about. We served the lamb with my dad’s homegrown new potatoes and steamed artichokes.
Here’s what we did:
Ingredients
1 boneless leg of lamb (about 4 to 5 lbs)
2 tablespoons fresh rosemary
2 tablespoons fresh thyme
2 tablespoons fresh oregano
4 cloves garlic
Olive oil
Salt & pepper
How to Prepare Roast Boneless Leg of Lamb with Fresh Herbs
Preheat the oven to 450ºF.
While the oven is heating, finely chop the herbs and garlic or use a food processor like we did.
Rub some oil on all sides of the lamb and season with salt and pepper. Spoon the herb/garlic mixture on the topside of the lamb and spread it out.
Place the lamb into a shallow roasting pan and roast for 30 minutes at 450ºF. Reduce the oven temperature to 375ºF and continue cooking until you reach the desired doneness as discussed above.
Let the roast rest for 5 to 10 minutes until the internal temperature reaches idea temp.
While the roast is resting, now is a great time to make some pan sauce. We poured the juices from the bottom of the roasting pan into a saucepan, added a cup of demi glace and some of the herbs that fell off the roast when removing the netting. Let the sauce reduce until it is thick enough to coat a spoon.
Ideally you would strain the sauce before serving, but we usually don’t and it tasted great. Chefs have told me that straining makes a big difference so I need to incorporate that technique into my repertoire.
We didn’t do this, but I bet a couple of tablespoons of mint jelly added to this sauce would be incredible.
on September 20th, 2007 at 11:29 am
Where do you get demi glace? Also, isn’t the net plastic? I always thought the red net around the lamb is plastic, so I get rid of that one, rub all the spices and herbs and then tie it with cooking twine. I never thought that the red net can be used in 450 degree oven.
on September 21st, 2007 at 7:12 am
You can learn more about demi glace, how to make it at home and where to buy it if you don’t want to spend the time at http://www.gatewaygourmet.com.
The net around our lamb was not plastic but if it were, I would read the label closely and see what it had to say. It doesn’t make sense to me that they would put a netting around the lamb to hold it together only to require you to remove it and tie it with cooking twine. But great question. I will check into it.
on January 3rd, 2008 at 11:06 am
I was just wondering approximately how long it would take for the lamb to finish roasting. Just an approximate time…is it 1-2 hours or 20 minutes?
on January 4th, 2008 at 8:11 am
Great question. A 4 to 5 pound boneless leg of lamb, rolled and tied, takes about 30 minutes per pound in a 325 degree oven. This of course depends on the exact size of your lamb and the actual temperature of your oven. Just because you set your oven at 325 doesn’t mean it is accurate. Also, where you place the meat in the oven and how often do you open the oven door.
Use this cooking time as an estimate but if you want your roasts to come out just the way you like them, use a meat or instant thermometer for doneness accuracy.
RG
on February 17th, 2008 at 2:46 pm
hi
Im cooking my lamb like this-I browned it on my grill after I seasoned it with garlic,salt,pepper. Then I put a bit of water in the pan and now Im roasting it at 375. is the water neccessary? Also can you marinate it?
on March 19th, 2008 at 2:16 pm
Hi, I bought a 2.61lb and 2.86lb boneless lamb leg and am planning on cooking them for Eater dinner. This is my first time cooking lamb and only my second time eating it, but with a husband who doesn’t care for Ham, Lamb it is! Can you recommend any good sides to accompany the lamb? And also about how many servings 2lbs of lamb contain?
Thank you!
on March 20th, 2008 at 12:32 pm
My concern is: three family members who believe they don’t like anything but beef (and ugh, hot dogs!). I’m cooking a 5# boneless leg o’ lamb - can I be a bit evasive and just tell them it’s “a roast…”?
I’m accompanying mine with acorn squash and fingerling potatoes…will do the sauce too…
on March 20th, 2008 at 4:39 pm
Thank you! Great information for someome who loves to cook–yet hasn’t ever made roasted lamb before! Perfect info–just what I needed! Happy Easter!
on March 21st, 2008 at 11:53 am
2 perfect sides:
- oven roasted potatoes (lately I’ve been mixing them with a bit of spicy shake-and-bake and the kids (including teens) can’t get enough of them)
- whole roasted tomatoes on top of rice
on March 22nd, 2008 at 9:27 am
I like the 425 for 30 minutes and 375 until done–but what would you guestimate total time for a 4-5 lb. boneless roast med. rare? ( I know I have to watch the oven thermometer but I need to know approx. when to put the roast in initially.)
on March 22nd, 2008 at 12:07 pm
I like the traditional carrots, asparagus and root veggies to go with lamb.
You can roast some red potatos and baby carrots together. I use like the mint jelly with lamb as thats the way mt mother had done it. Some sauteed spinach w/ garlic and S & P would be tasty and quick
on March 23rd, 2008 at 7:06 am
Yes, get the little mini potatoes both white and red. Par boil them until a fork can go through them then saute them with garlic and shallots. He’ll love it.
on September 28th, 2008 at 8:08 am
I’m with HOBBYLOU..I’ve been cooking for my family for over 35 years. My husband says I’m the best cook in the world…BUT! you need to be more CLEAR with new cooks. HOW MANY MINUTES PER POUND???!!! A cook needs to know what time to start a roast in order to tell her guests when dinner is to be expected. How on earth can you time your vegetables, etc. if you don’t know WHEN the roast will be “DONE”?
on September 28th, 2008 at 10:51 am
Hi Betty,
Great points and yes it is a good idea to know approximately how long a roast will take to cook but as I say in the post, there are many variables to consider.
“HOW MANY MINUTES PER POUND” can depend on the cut of meat, how thick it is, the accuracy of your oven temperature dial, where you oven hot spots are, what type of pan you using, how thick is it, what is it made of, what altitude you are cooking at and what you consider medium or medium well done.
You can see there are lots of things to consider when roasting that will alter how long a roast will take. Saying that, we can look at various cooking charts detailing how long a boneless leg of lamb will take to cook based on it’s weight & cooking temperature in order to time our side dishes.
So a boneless tied leg of lamb weighing 4 - 7 pounds roasted at 325 degrees should take about 20 to 25 minutes per pound to reach medium to medium rare.
But what if you want to use the high temperature cooking technique and start at 450 degrees F and then lower the temperature?
I will work on a chart for approximate cooking times but I highly recommend you purchase a good instant meat thermometer to figure out exactly the best time to take a roast out of the oven to be at your desired doneness.
on October 1st, 2008 at 11:06 pm
Please Respond A.S.A.P.
I have written many people and many sites and no one has ever contacted me back. I would like to enjoy lamb and know better how to cook it.
I would like to know if there is any way to take away the strong musky flavor that lamb has?
Thank you in advance on your response. God’s Blessing
on October 8th, 2008 at 9:22 pm
OK Here goes nutten….
Regarding cooking times, I have a 3.12lb. Boneless Lamie Pie Leg and I am going to use the 450 degree (initial) for 30 min. reducing to 375 method until 130 internal temp, and I will get back with you all regarding timing at an adjusted heat method.
Love & Lamb Sandwiches Tomorrow Forever….
Casey
on October 9th, 2008 at 5:16 pm
All Righty Then…
The Boneless leg roast entered the 450 degree oven at 10:00pm ( I panicked somewhat and reduced the temp to 350 after 20 min)
In One Hour the internal temp was 118.
13 minutes later I registered a 130 internal temp, removed from oven and let rest in a loose tent for 20 or so min. while I cranked the oven back up to 450 and roasted root vegetables (in the drippings) to dark rustic colors unknown to the free world.
In summary … 23.5 min per lb. at this varied temp method.
Wonderful Medium Rare doneness, very flavorful demi glace sauce reduction.
Waaaayyyy to nice of a meal to enjoy with just your cat.
(But don’t tell him that)
Thanks for sharing this Dynomite Dinner recipe
on October 9th, 2008 at 5:26 pm
PS …I used a 9X13 X2 in. glass roasting vessel with a wire rack.
I hear the Lamb Sandwich calling me as I type…
on December 16th, 2008 at 8:42 pm
love your website!! I am going to cook my first boneless leg of lamb on Sunday. Your website helped immensely!! thanks!!
I am going to do 450 for 30 minutes then reduce to 325 til 130 degrees. then wrap in foil for 20 minutes!!
thanks
on March 22nd, 2009 at 6:32 pm
I have the butcher bone & stuff with garlic , Italian parsley, salt & pepper. I make brussel sprouts w/ fried bacon garlic & sauted onions. Serve with Musselmans chunky applesauce. Make roasted potatoes in separate pan or in with roast add some water to leg with parsley, onions sliced, salt & pepper. Mangia, Filia me
on April 6th, 2009 at 12:34 pm
I have a large family to feed on Easter Sunday. I will be roasting two 6 lb. boneless leg of lambs. I’d like to cook the lamb a day ahead. What temperature would you recommend removing the lambs so they can be reheated the following day? What temperature should the lambs be reheated at and how long should they cook? When reheating should I add beef broth or water to keep it from drying out and should I cover the pan. I’m considering placing a 1/2 a can of coke cola and 1/2 a can of beer in the roaster for additional tenderness. What are your thoughts on this. Lamb is expensive and I don’t want to mess this dinner up.
Thank you for your input.
on April 7th, 2009 at 10:41 am
Since the lamb is the star of the show and is expensive, I would cook the other dishes the day before (whichever ones lend themselves to that) and roast the lamb on Easter. The reason is that reheating a cut of meat that you originally roasted dry (not as a stew or a braise) will never be as good the second day, unless you just slice it and serve it cold or at room temperature.
If you absolutely must reheat the meat the next day, I would slice it the way you would to serve it and lay it out in a baking dish and barely cover with some chicken or beef broth. Then, I’d cover the dish with some foil and reheat in a low oven (300-325) until reheated.
Personally, I would not use beer or Coke–these liquids, since they are somewhat acidic, could possibly help to tenderize a tough piece of mutton with long, low cooking, but this would be more like a braise or a stew. For a tender leg of lamb, I’d stay away from either of these and just stick with a light broth or stock.
I cannot really give you guidelines regarding cooking times or temperatures, because I don’t know how your family likes to eat their lamb.
My mom used to cook hers until it was gray all the way through, but, if I’m roasting lamb, I like mine medium rare. There is a doneness chart on my Reluctant Gourmet website that you can refer to: http://www.reluctantgourmet.com/doneness_chart.htm
Hope this helps,
RG
on April 7th, 2009 at 8:42 pm
stupid question: When you use a meat thermometer to check the lamb, do you leave the thermometer in the lamb the whole time, or put it in every now and again to check the temp?
on April 8th, 2009 at 9:26 am
Great site; lots of useful information and discussion. Thank you
on April 9th, 2009 at 9:40 am
Looks great–I’ll try it for this Easter Sunday. But I’m just curious–Williams Sonoma has a demi glace (chicken, beef, veal–no lamb), that costs $29. They say you only need a couple of tablespoons since it is so concentrated. Has anyone tried it?
on April 9th, 2009 at 4:14 pm
We’re going to church and need to place the leg in the oven and set the oven to automatically come on while we are gone…we’ll be eating upon our return. I’ve cooked lamb many times but have always been home to place it in the oven. Any comments or suggestions?
on April 10th, 2009 at 2:43 am
brett: if you have a wireless thermometer that can handle the heat then you keep it in. otherwise most people have a regular thermometer which will melt if you leave it in the oven. also dont check the temp ever now and then. use a cooking chart and then check after the time it said for the desired wellness. also make sure take the temp from the middle of the roast.
on April 10th, 2009 at 8:43 pm
I am doing a boneless leg of lamb for Easter dinner also. I will serve it with roasted new potatoes, fresh baby asparagus and home-made orange rolls, just as my mother used to! Then I make lamb pot pie for leftovers.
on April 10th, 2009 at 10:28 pm
You asked a good question about thermometers. There are two different kinds. One you leave in for the whole time, and one you insert to check the doneness and take out. The first kind, the one you leave in, is often glass and actually looks like a thermometer. This will have a metal gauge on top so you can read the temperatures. The instant read thermometer is a newer model. It is all stainless steel and looks like a probe with a small dial on the top that reads the temperature. You can often find these in coffee houses (like Starbucks) because they use them while checking the temperature of the milk for lattes.
on April 10th, 2009 at 10:35 pm
I forgot to add to my comment about the thermometers some important info. Both types work well. With the meat thermometer that you leave in, make sure that this never touches the bone of the meet you are reading; you will get an inaccurate reading. I guess that actually goes for both types. You have to make sure that you stick it into the thickest part of the meat. As stated above, there are many different discussions about what is the temperature of rare, medium and well. I have always found that the mark on the old glass thermometers that states medium or rare is always too high of a temp and far too overdone. I would go with the recommendations of this website and use their temperatures as your gauge.
on April 11th, 2009 at 4:08 pm
Am roasting a 2.4 boneless butterflied half leg of lamb and wonder how long to cook it if the temp in the oven is 350 degrees.
Want to cook it not much more than rare.
on April 11th, 2009 at 4:30 pm
If you’re using the old fashioned kind of meat thermometer, you can leave it in the whole time and watch the temperature go up through the closed oven door. Remove when it reads the temp you want, then cover. This way you’re not opening and closing the oven.
on April 14th, 2009 at 6:01 am
Just cooked boneless lamb for easter.thought 140 was mediuim rare but was wrong. Way overdone. Will take out at 128 or 130 next time.