Wash the tongue carefully, and let it lie in cold water for several hours before cooking—over night, if possible. Lay it in a kettle of cold water when it is to be cooked; bring the water to a boil slowly, and let it simmer until the tongue is so tender that you can pierce it with a fork. A large tongue should be over the fire about four hours. When it has cooled in the liquor in which it was boiled, remove the skin with great care, beginning at the tip, and stripping it back. Trim away the gristle and fat from the root of the tongue before serving it. Serve with drawn butter or lemon sauce.