2 medium red and/or green sweet peppers, cut into thin strips
1 large onion, thinly sliced and separated into rings
4 whole-wheat frankfurter buns, split
½ cup shredded reduced-fat Cheddar or reduced-fat Monterey Jack cheese (2 ounces)
Preheat broiler. Trim fat from steak. Sprinkle steak with garlic-pepper seasoning. Place seasoned steak on the unheated rack of a foil-lined broiler pan. Broil 3 to 4 inches from heat until desired doneness. Allow 15 to 17 minutes for medium-rare (145°F) or 20 to 22 minutes for medium (160°F).
Meanwhile, coat an unheated extra-large nonstick skillet with cooking spray (see Tip). Preheat skillet over medium heat. Add sweet peppers and onion. Cover and cook for 5 minutes. Uncover and cook about 5 minutes more or just until tender, stirring occasionally.
Place split buns on a large baking sheet. Broil 4 to 5 inches from heat for 1 to 2 minutes or until lightly toasted. Remove bun tops from baking sheet; set aside. Slice steak into bite-size strips. To assemble, divide steak strips and sweet pepper mixture among bun bottoms. Sprinkle with cheese. Broil 4 to 5 inches from the heat for 1 to 2 minutes or until cheese is melted. Add bun tops.
Tip: If you do not have an extra-large nonstick skillet, use a large nonstick skillet and cook the sweet peppers and onions separately.