Step 1: Prepare your ingredients. If slicing your own steak, place it in the freezer for 20-30 minutes to firm up, then slice as thinly as possible against the grain. Thinly slice the onions and bell pepper (if using). Have your cheese ready.
Step 2: Heat 1 tablespoon of oil in a large skillet or griddle over medium heat. Add the sliced onions and bell peppers. Cook, stirring occasionally, for 10-15 minutes, or until deeply caramelized and tender. Season with a pinch of salt and pepper. Remove from the skillet and set aside.
Step 3: Increase the heat to medium-high. Add the remaining 1 tablespoon of oil to the skillet. Working in batches if necessary to avoid overcrowding, add the thinly sliced ribeye steak. Season generously with salt, pepper, and garlic powder (if using).
Step 4: Cook the steak for 2-3 minutes, stirring and chopping it with your spatula as it cooks, until it's just browned and cooked through. Avoid overcooking, as this can make the steak tough. If cooking in batches, add all cooked steak back to the skillet.
Step 5: Return the cooked onions and peppers to the skillet with the steak. Mix everything together well. Divide the mixture into 4 equal portions in the skillet, forming mounds.
Step 6: Place 2-3 slices of provolone cheese (or a generous dollop of Cheez Whiz/American cheese slices) over each mound of steak and vegetables. Let the cheese melt for about 1-2 minutes, you can cover the skillet briefly to speed up the melting process.
Step 7: While the cheese is melting, lightly toast your hoagie rolls, cut-side down, in a separate dry skillet or under the broiler until golden. This helps prevent them from getting soggy.
Step 8: Once the cheese is melted and gooey, carefully scoop one portion of the steak and cheese mixture directly into each toasted hoagie roll using a spatula. Serve immediately and enjoy your authentic Philly cheesesteak!