Prepare the Steak: Slice the steak very thin (partially freezing it for 15-20 minutes helps) and season with salt and pepper.
Cook the Onions: Sauté the diced onions in 1 tablespoon of vegetable oil over medium heat until caramelized, about 5-7 minutes. Remove and set aside.
Cook the Steak: In the same skillet, cook the steak over medium-high heat for 2-3 minutes, stirring occasionally until browned but tender.
Add the Cheese: Lower the heat, spread the steak in the skillet, and top with 4 torn slices of provolone cheese. Let it melt, then stir to combine.
Toast the Rolls: Lightly toast the hoagie rolls in the oven or skillet until the inside is crisp.
Assemble the Sandwiches: Fill the rolls with the steak and cheese mixture, top with caramelized onions, and place a slice of provolone over each sandwich.
Broil (Optional): Place the sandwiches under a broiler for 1-2 minutes to melt the cheese and crisp the edges. Serve hot and enjoy!