Combine first 6 ingredients in a bowl.
Combine tomatoes and next 5 ingredients (tomatoes through kale) in a bowl. Divide balsamic vinaigrette and vegetable mixture evenly between 2 large zip-top plastic bags. Seal; marinate in refrigerator 1 hour, turning bags occasionally.
Remove vegetables from bags; reserve marinade. Prepare grill. Place vegetables on grill rack coated with cooking spray; grill 7 minutes on each side or until onion is tender, basting with reserved marinade.