Clean and parboil the Sweetbreads as already shown in recipe. Chop an onion very fine and place it in a saucepan with a tablespoonful of butter. Let them simmer without browning; add one bay leaf, one sprig of thyme, one-half clove of garlic, a teaspoonful of prepared mustard, and mix well. Then add a pint of water and stir well; then add the Sweetbreads which have been chopped very fine and formed into Crepinettes, or little fringed Balls, by patting with the hand; let them simmer for about fifteen minutes longer. Serve with any sauce, preferably a Cream Sauce.