Heat 1 tablespoon of vegetable oil in a large skillet over medium-high heat.
Add the sliced onions to the skillet and sauté for 5-7 minutes until they are soft and caramelized. Remove onions from the skillet and set aside.
Add the remaining 1 tablespoon of vegetable oil to the skillet and increase heat to high.
Add the thinly sliced ribeye steak to the skillet in a single layer. Season with salt and black pepper.
Cook the steak for 2-3 minutes without stirring to allow browning, then stir and cook for another 2-3 minutes until cooked through.
Reduce heat to medium and return the sautéed onions to the skillet with the steak. Mix well.
Divide the steak and onion mixture evenly into four portions in the skillet.
Place two slices of provolone cheese on top of each portion and allow it to melt, about 1-2 minutes.
While the cheese melts, slice the hoagie rolls lengthwise without cutting all the way through.
Using a spatula, scoop each steak, onion, and cheese portion into a hoagie roll.
Serve immediately while hot.