Heat coals or gas grill for direct heat. Spray large piece of heavy-duty aluminum foil with cooking spray.
Place tomatoes, onion and bell pepper on foil. Wrap foil securely around vegetables. Cover and grill foil packets, seam sides up, 4 to 6 inches from medium heat 6 minutes, turning once.
While vegetables are grilling, mix green onions, vinegar, thyme, salt and pepper sauce in medium bowl; set aside.
Spray fish and hinged wire grill basket with cooking spray.
Place fish in basket; add to grill with vegetables. Cover and grill fish 7 to 8 minutes, turning once, until fish flakes easily with fork.
Place fish on serving platter; keep warm. Coarsely chop grilled vegetables. Toss vegetables, parsley and green onion mixture; spoon over fish.