Saute meat and onions in butter. Sprinkle flour over and mix well. Add lettuce, water, salt, pepper, and parsley or dill. Simmer, covered, until meat is tender (about 1 hour). Remove from heat.
For egg and lemon sauce: beat egg yolks with 2 tablespoons of water. Add lemon juice. Beat in, by spoonfuls, about 1/2 cup of the lamb gravy. Pour egg mixture gradually over meat and gravy, stirring all the time. Serve hot.
This dish is also delicious when prepared with artichokes or endive, instead of lettuce.