Let them lie in cold salt and water for half an hour after skinning them; put into a saucepan with a tablespoonful of chopped onion for each pound of fish; cover with cold water and stew until they are tender. Take them out, salt, pepper, and butter them, and keep hot over boiling water, while you add to the water in which they were cooked, a great spoonful of butter cooked to a roux with a tablespoonful of flour, and stirred into three tablespoonfuIs of cream (also hot), and a little chopped parsley. Stir until it boils, and pour the sauce over the fish. Let them stand in it for five minutes and serve. A beaten egg will enrich this sauce.