Start by preheating your oven to 375°F.

Cut or tear off 4 pieces of parchment paper from the roll that are about 12 inches long. Lay them down on the counter so they flatten out a bit.

Prep all your ingredients and have them ready to assemble. The halibut should be cut into 4 equal sized pieces.

Position a piece of parchment paper in a shallow bowl - I used a shallow soup bowl and started adding a quarter of the sliced leeks, mushrooms, garlic and tomatoes to the center of the paper. The bowl is there to keep all the ingredients together in the center.

Next add a piece of fish on top of the vegetables and drizzle some olive oil over the top of the fish

Season with salt and pepper or your favorite fish seasoning and you are ready to start folding the paper. Make a pouch with the parchment paper by folding the paper in half and then fold it over on itself several times to secure it shut.

Then fold up the sides of the paper to make a pouch. You'll repeat this process with the remaining parchment and ingredients and arrange on a baking sheet.

Roast the parchment pouches for about 15 minutes. How long will depend on the size & thickness of the fish and the accuracy of your oven.