2 tsp extra-virgin olive oil
1 medium onion, sliced
8 oz mushrooms, sliced
1 red or green bell pepper, sliced
2 tbsp minced fresh oregano, or 2 tsp dried
1/2 tsp freshly ground black pepper
1 lb sirloin steak, trimmed and thinly sliced
1/2 tsp salt
1 tbsp all-purpose flour
1/2 cup sliced hot banana peppers (optional)
1/4 cup reduced-sodium chicken broth
3 oz thinly sliced reduced-fat provolone cheese
4 whole-wheat buns, split and toasted
 Heat oil in a large nonstick skillet over medium-high heat. Add onions and stir until brown, 2-3 minutes. Add mushrooms, bell peppers, oregano, and black pepper and stir until the vegetables are soft, about 7 minutes.
 Add sirloin and salt and cook, stirring, until the beef is just cooked through, about 4 minutes.
 Reduce heat to low; sprinkle the vegetables and beef with flour; stir to coat. Stir in banana peppers (optional) and broth; bring to a simmer. Remove from the heat, lay cheese slices on top of the vegetables and beef, cover, and let stand until melted, 1-2 minutes.
 Divide into 4 portions with a spatula, leaving the melted-cheese layer on top. Scoop a portion onto each toasted bun and serve immediately.
Nutritional Information Per Sandwich:
440 calories, 45 g protein, 31 g carbs, 15 g fat, 5 g fiber