Open and clean the fish, cut off its head (or not as preferred), cut out the backbone from the head to within two inches of the tail, and fill with the following mixture:  Soak stale bread in water, squeeze dry; cut a large onion in pieces, fry in butter, chop fine, add the bread, two ounces of butter, salt, pepper, and a little parsley or sage; heat thoroughly, and when taken from the fire, add two yolks of well-beaten eggs; stuff, and when full, wind the fish several times with tape, place in baking pan, baste slightly with butter, and cover the bottom of pan with water; serve with the following sauce:  Reduce the yolks of two hard-boiled eggs to a smooth paste, add two tablespoons olive oil, half teaspoon mustard, and pepper and vinegar to taste. Buckeye Cookery - 1877