1. Split each pita bread halfway around edge with knife; separate to form pocket.
2. Mix yogurt, mint and sugar in small bowl. Stir in cucumber.
3. Mix lamb, water, lemon juice, salt, cumin, oregano, pepper, garlic and onion. Shape mixture inot 4 think patties.
4. Heat oil in 10-inch skillet over medium heat. Cook patties in oil 10 to 12 minutes, turning frequently, until no longer pink in center. Place cooked patty in each pita pocket. Top with yogurt mixture, lettuce and tomato.