HEAT grill to medium-high heat.
COMBINE tomatoes, 2 Tbsp. dressing and garlic. Place fish in center of large sheet double-layer heavy-duty foil sprayed with cooking spray. Sprinkle with black pepper; top with tomato mixture. Fold foil to make packet.
GRILL 8 to 10 min. or until fish flakes easily with fork. Meanwhile, toss remaining vegetables with remaining dressing; grill 5 min. on each side.
CUT slits in foil to release steam before opening packet. Sprinkle fish with cheese. Serve with grilled vegetables and quinoa.