1. Stir yogurt, cucumber, mint, salt and pepper in a small bowl. Refrigerate until ready to serve.
2. Combine lemon juice, garlic, oregano, salt and pepper. Layer lamb and lemon juice mixture.
3. Cover and cook on HIGH 3 hours or LOW 6 hours until lamb is tender. Remove lamb; discard fat and bone. Thinly slice lamb.
4. Serve on warmed pita bread topped with onion, tomatoes and cucumber yogurt sauce.
TEST KITCHEN TIP: Try using jarred garlic (available in your supermarket) if you’d rather not chop fresh garlic. If you don’t like lamb, try substituting pork or beef for this recipe instead.