Chop a cooked onion and mix it with three tablespoonfuls of breadcrumbs. Add one ounce of butter, salt, and pepper to taste, a little chopped parsley, and one egg. When thoroughly mixed stuff the fish with the mixture, butter a paper bag, roll the fish in flour, place in the bag, dot over with small pieces of butter, seal up, and cook for twenty minutes in 300 Fahr.