Heat 1 tablespoon of vegetable oil in a large skillet over medium-high heat.
Add the thinly sliced onions and sauté for about 5-7 minutes until they are soft and lightly caramelized. Remove onions from the skillet and set aside.
Add the remaining 1 tablespoon of vegetable oil to the skillet.
Add the thinly sliced ribeye steak to the skillet in a single layer. Season with salt and black pepper.
Cook the steak for 3-4 minutes, stirring occasionally, until browned and cooked through.
Return the sautéed onions to the skillet with the steak and stir to combine.
Divide the steak and onion mixture into four portions in the skillet.
Place 2 slices of provolone cheese on top of 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 and toast them lightly.
Using a spatula, scoop each portion of the steak, onion, and melted cheese mixture into the toasted hoagie rolls.
Serve the Philly Cheesesteaks hot.