From "The Complete Book of Greek Cooking," edited by Katherine R. Boulukos (Harper-Collins). In a large skillet, brown lamb shanks in oilve oil. Add half cup water, garlic, half teaspoon salt, oregano and pepper. Cook, covered, over low heat for one hour, or until tender. Rinse lentils and drain. In a medium saucepan, combine lentils, 3 cups water, onion, celery, bay leaf and 1- half teaspoons of salt. Simmer, uncovered, 50-60 minutes, or until vegetables are tender. Pour mixture into greased baking dish. Top with meat, lemon slices. Bake 20-25 minutes, until liquid is absorbed and lentils are tender. Discard onion and bay leaf.