Ingredients for 4 servings:
1. 1 (1 lb) flank steak, trimmed
2. 1/2 teaspoon salt
3. 1/4 teaspoon fresh ground black pepper
4. 4 slices red onions (1/4 inch thick slices)
5. 1/4 cup ketchup
6. 2 tablespoons light brown sugar
7. 1 tablespoon cider vinegar
8. 1 tablespoon Worcestershire sauce
9. 1/4 teaspoon dried chipotle powder
10. 4 (3 ounce) hoagie rolls, split

Directions:
1. Heat a grill pan over medium high heat. Coat pan with cooking spray.
2. Sprinkle steak evenly with salt and pepper. Add steak to pan; cook 6 minutes on each side or until desired degree of doneness. Remove steak from pan; let stand 10 minutes.
3. Add onion to pan; cook 3 minutes on each side or until lightly browned.
4. Remove from pan; cool.
5. Combine ketchup and next 4 ingredients in a large microwave safe bowl, stirring well. Microwave on high 1 minute or until thoroughly heated.
6. Cut steak diagonally across grain into thin slices.
7. Add steak to ketchup mixture; toss to coat. Divide steak mixture evenly among bottom halves of rolls; top each serving with one onion slice.
8. Place top half of roll on each sandwich.

Enjoy your meal!