In a bowl, combine the thinly sliced ribeye or sirloin with salt, pepper, garlic powder, and Italian seasoning (if desired). Toss well to ensure each piece is evenly coated and ready for cooking.

Heat olive oil in a large skillet over medium heat. Add the sliced bell pepper, onion, and mushrooms (if using). Sauté for about 5-7 minutes until the vegetables are softened and vibrant, then remove them from the skillet and set aside.

In the same skillet, add the seasoned steak. Cook for about 3-5 minutes, stirring frequently, until browned and cooked to your liking. The steak should be tender and juicy.

Return the sautéed vegetables to the skillet with the steak, mixing them together. Cook for an additional 1-2 minutes, just until everything is heated through and harmonious.

Preheat your oven to 350°F (175°C). While it's heating, slice the sub rolls open to create a pocket for the filling, ensuring they’re ready to hold all the deliciousness.

Evenly divide the steak and vegetable mixture among the rolls. Top each with a slice of provolone or mozzarella cheese, allowing the cheese to get all melty and delicious.

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

Remove the sandwiches from the oven and let them cool for a minute. Serve hot, with hot sauce on the side for those who crave a little heat.