Step 1: Prepare your ingredients. If slicing your own ribeye, partially freeze it for 30-45 minutes, then slice against the grain as thinly as possible. Thinly slice the onions and bell pepper (if using). Have your cheese slices ready.
Step 2: Heat 1 tablespoon of olive oil in a large cast-iron skillet or griddle over medium-high heat. Add the sliced onions and bell pepper. Sauté, stirring occasionally, until the onions are deeply caramelized and tender, about 10-15 minutes. Season lightly with salt and pepper. Remove the vegetables from the skillet and set aside.
Step 3: Increase the heat to high. Add the remaining 1 tablespoon of olive oil to the same skillet. Once the oil is shimmering hot, add the thinly sliced ribeye steak in a single layer. Cook in batches if necessary to avoid overcrowding, which steams the meat instead of searing it.
Step 4: Sear the steak quickly for 1-2 minutes per side, breaking it up with a spatula as it cooks, until it’s nicely browned and cooked through but still tender. Season generously with salt and freshly ground black pepper.
Step 5: Push the cooked steak to one side of the skillet. Return the caramelized onions (and peppers) to the pan, mixing them with the steak. Divide the steak and onion mixture into four portions directly in the skillet.
Step 6: Place two slices of provolone or American cheese over each portion of the steak and onion mixture. You can cover the skillet with a lid for 1-2 minutes to help the cheese melt perfectly and become gooey.
Step 7: While the cheese is melting, lightly toast the insides of the hoagie rolls on a separate dry pan or directly on the skillet if there’s space. This adds a nice crunch and helps prevent the roll from getting soggy.
Step 8: Once the cheese is melted and gooey, use a spatula to scoop each portion of the cheesy steak mixture directly into a toasted hoagie roll. Serve immediately and enjoy your homemade philly cheese steak sandwich recipe!