Serve with harissa, a hot sauce sold in Middle-Eastern markets.
Combine all ingredients except the cooking spray in a large bowl. Cover and marinate in refrigerator 2 hours.
Prepare grill to medium-high heat.
Thread lamb pieces onto each of 8 (8-inch) skewers. Lightly coat lamb with cooking spray. Place brochettes on grill rack coated with cooking spray; grill 5 minutes on each side or until desired degree of doneness.