How to Make It
Preheat grill to high.
Combine first 7 ingredients in a bowl. Thread chicken onto 4 (10-inch) skewers. Thread tomatoes, bell peppers, and onion alternately onto 8 (10-inch) skewers. Brush chicken and vegetable kebabs with half of buttermilk mixture.
Coat grill grates with cooking spray. Place kebabs on grill; grill 5 minutes. Turn and grill 5 minutes or until chicken is done, brushing chicken and vegetables with remaining buttermilk mixture. Remove kebabs from grill. Sprinkle with salt and black pepper.