1. Combine first 6 ingredients in a large heavy-duty zip-top plastic bag; add lamb, and seal bag. Marinate in refrigerator 12 to 24 hours, turning bag occasionally.
2. Prepare grill.
3. Remove lamb from bag, reserving marinade. Place marinade in a saucepan. Bring to a boil; remove from heat. Thread lamb, bell pepper, tomatoes, and onion alternately onto 12 (10-inch) skewers. Place skewers on grill rack coated with cooking spray. Grill, covered, 5 minutes on each side or until desired degree of doneness, turning and basting kebabs frequently with marinade.
carbo rating: 6