1. Prepare grill.
2. Coat zucchini and bell pepper halves with cooking spray; place on grill rack. Cover and grill 5 minutes on each side or until bell pepper is charred and zucchini is tender.
3. Remove vegetables from grill; cut into 1-inch pieces. Place in a medium bowl. Stir in corn and remaining 3 ingredients, tossing gently to combine.