Preheat oven to 400°F. Spray large nonstick skillet with cooking spray; heat on medium-high heat until hot. Remove steak from bag; discard marinade in bag. Place steak in skillet; sprinkle with pepper. Place onions around steak. Cook 3 min. or until bottom of steak is well browned. Turn steak over; remove from heat. Combine broccoli, carrots and remaining dressing; mix with onions. Wrap handle of skillet in heavy-duty foil. Place skillet in oven.