Saute meat and onions in butter. Sprinkle flour over meat and mix well. Add lettuce, water, salt, pepper and parsley or dill. Cover and simmer until meat is tender (about 1 hour). Remove from heat. For egg and lemon sauce: whisk egg yolks with 2 tablespoons of water. Add lemon juice. Add, by spoonfuls, about ½ cup of the lamb gravy, whisking continuously. Pour egg mixture gradually over meat and gravy, stirring all the time. Serve hot. Makes 4 servings.