Fill a sink 1/2 full of cold water. Add the mussels and toss them around. Pull the beards and scrape off any barnacles from each mussel (inspecting them to make sure that they are tightly closed). Discard any bad mussels. Keep the cleaned mussels out of the water in the refrigerator until ready for use. Do not keep them more that a few hours after washing.
Chop the shallots and parsley.
Put the shallots and white wine into a large stainless steel pot. Add the mussels and cover. Steam them over high heat until the mussels have opened. Shake the pot to be sure that all the mussels are cooked.
Put the mussels into a large bowl. Decant the mussel liquor into a saucepan and bring to a boil.
Add the butter and chopped parsley.
Pour this sauce over the mussels and serve immediately.
I hope your readers enjoy this. I know all of my friends do.