Slice the hoagie rolls 3/4 of the way through and spread the softened butter mixed with pressed garlic onto the cut sides. Toast the buns until golden brown and set aside.
In a skillet, sauté the diced onions until caramelized, then transfer them to a bowl.
Increase the heat to high and add oil to the skillet. Spread the thinly sliced steak in an even layer, letting it brown for a couple of minutes undisturbed. Flip the steak, season with salt and pepper, and sauté until fully cooked. Stir in the caramelized onions and bell peppers.
Divide the steak mixture into 4 portions and top each with 2 slices of provolone cheese. Turn off the heat and allow the cheese to melt.
Spread a thin layer of mayonnaise on the toasted side of each roll. Place a roll over each portion of steak and use a spatula to transfer the cheesy beef mixture into the rolls.
Serve warm and enjoy the ultimate Philly Cheesesteak experience!