Step 1: Prepare the Steak and Vegetables

1. Season the Steak: In a bowl, season the thinly sliced steak with salt, pepper, garlic powder, and Italian seasoning (if using). Toss to coat evenly.
2. Sauté the Vegetables: In a large skillet, heat olive oil over medium heat. Add the sliced bell pepper, onion, and mushrooms (if using). Sauté for about 5-7 minutes until the vegetables are softened. Remove them from the skillet and set aside.

Step 2: Cook the Steak

1. Cook the Steak: In the same skillet, add the seasoned steak. Cook for about 3-5 minutes, stirring frequently, until the steak is browned and cooked to your desired doneness.
2. Combine with Vegetables: Return the sautéed vegetables to the skillet with the steak and mix well. Cook for an additional 1-2 minutes to heat through.

Step 3: Assemble the Sandwiches

1. Prepare the Rolls: While the steak and vegetables are cooking, preheat your oven to 350°F (175°C). Slice the sub rolls open, but not all the way through, creating a pocket.
2. Fill the Rolls: Divide the steak and vegetable mixture evenly among the rolls. Top each sandwich with a slice of provolone or mozzarella cheese.

Step 4: Bake the Sandwiches

1. Melt the Cheese: Place the filled sandwiches on a baking sheet and bake in the preheated oven for about 5-7 minutes, or until the cheese is melted and the rolls are slightly toasted.

Step 5: Serve

1. Cool Slightly: Remove the sandwiches from the oven and let them cool for a minute.
2. Enjoy: Serve the steak bomb sandwiches hot, with hot sauce on the side if desired.