Step 1

Add onions to small skillet sprayed with cooking spray; cook and stir on medium-high heat 3 to 4 min. or until crisp-tender. Remove onions from skillet; cover to keep warm.

Step 2

Add steak to same skillet; cook 3 min. on each side or until medium doneness (160ºF). Let stand, loosely covered, 3 min. Cut steak across grain into thin slices; return to skillet. Add barbecue sauce. Cook on medium-low heat 4 min. or until sauce is heated through.

Step 3

Fill bread slices with meat mixture, onions and cheese.