1. Heat 1 tbsp oil in a large skillet over medium heat. Add the onions and cook for about 4 minutes, to soften. Add the peppers, mushrooms, remaining oil, salt (in moderation), and pepper. Continue to cook for about 8 minutes.
2. Meanwhile, toast the scooped out hoagie buns in the oven. Divide the vegetable filling and roast beef among the hoagie rolls. Top with provolone and set under the broiler for 2–3 minutes, until the cheese is melted. Serve warm.
Per serving: 374 calories, 15g fat, 4g saturated fat, 13mg cholesterol, 501mg sodium, 47g carbohydrate, 4g fiber, 9g sugar, 15g protein