Step 1: Cook the Steak
Heat olive oil in a large skillet or griddle over medium-high heat. Add the sliced steak and cook for 2-3 minutes, or until browned but not fully cooked. Remove the steak and set aside.
Step 2: Sauté the Vegetables
In the same skillet, add the onion, bell pepper, and mushrooms. Cook for 5-7 minutes, or until softened and slightly caramelized. Season with salt, black pepper, and garlic powder.
Step 3: Combine and Melt Cheese
Return the steak to the skillet and toss with the vegetables. Divide the mixture into four portions and top each with 2 slices of provolone cheese. Cover the skillet and let the cheese melt, about 1-2 minutes.
Step 4: Assemble the Sandwiches
Scoop the steak and vegetable mixture into the toasted hoagie rolls. Garnish with fresh parsley and serve hot.