De-beard and scrub mussels.
Cook until open with ¾ cup water and lemon slice.
Shuck and mince mussel meat, save ½ shells, reserve liquid.
Sauté onion in olive oil until wilted, add prosciutto and garlic, sauté.
Stir in tomato sauce, mussel liquid, the mussel meat, parsley salt & pepper.
Place in clean container. Label, date, initial and refrigerate.