Directions

1. Coat grill rack with nonstick cooking spray. Preheat grill to high (400F to 450F). In a large bowl combine beef and taco seasoning; mix well. Divide into 4 equal portions; shape each portion into patties 1/2-inch thick. Season with salt and pepper to taste.
2. Place beef patties, bell pepper quarters and onion slices on grill. Grill bell peppers 3 to 4 minutes per side or until tender. Grill onion 4 to 5 minutes per side or until tender. Grill patties 6 to 8 minutes per side for medium (160F) or to desired doneness. About 1 minute before patties are done, place 1 cheese slice on each patty.
3. Remove peppers, onions and patties from grill. Cover loosely to keep warm; let stand 5 minutes.
4. Spread the bottom half of each roll with mayonnaise (if desired); add 1 onion round and 1 burger. Dice the bell peppers and place on each burger. Serve immediately.