Cut the hoagie rolls 3/4 of the way through using a serrated knife. Dice the onions and thinly slice the ribeye steak.

In a small bowl, combine 2 Tbsp of softened butter with 1 minced garlic clove. Spread this garlic butter on the cut sides of the hoagie rolls. Toast the rolls on a skillet, cooktop, or griddle over medium heat until golden brown. Set aside.

Heat 1 Tbsp of oil in your pan or cooktop. Sauté the diced onions until caramelized, then transfer to a bowl.

Increase the heat to high and add another 1 Tbsp of oil. Lay the thinly sliced steak in an even layer on the pan. Let it brown undisturbed for a couple of minutes, then flip and season with 1/2 tsp of salt and 1/2 tsp of black pepper. Cook until the steak is fully done, then mix in the caramelized onions.

Divide the steak and onion mixture into 4 portions. Place 2 slices of provolone cheese on each portion, then turn off the heat to allow the cheese to melt without overcooking the meat.

Spread a thin layer of mayonnaise on the toasted side of each hoagie roll. Place a toasted roll over each portion of the cheesy steak, then use a spatula to scoop the mixture into the roll as you flip it over. Serve warm.