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 same skillet and increase heat to high.
Add the thinly sliced ribeye steak to the skillet, season with salt and black pepper, and cook for 3-4 minutes, stirring frequently until the steak is browned and cooked through.
Return the sautéed onions to the skillet with the steak and mix well.
Divide the steak and onion mixture into four portions in the skillet.
Place two slices of provolone cheese over each portion and allow the cheese to melt, about 1-2 minutes.
While the cheese melts, slice the hoagie rolls lengthwise without cutting all the way through.
Once the cheese has melted, use a spatula to transfer each portion of steak, onions, and cheese into a hoagie roll.
Serve immediately while hot.