If your steak is not pre-sliced, partially freeze it for about 30 minutes to make slicing easier. Slice the ribeye as thinly as possible against the grain.
Heat the vegetable oil in a large skillet or on a griddle over medium-high heat.
Add the sliced onions (and bell pepper, if using) and cook until softened and lightly browned, about 5-7 minutes. Remove onions and peppers from the skillet and set aside.
Add the thinly sliced steak to the hot skillet. Cook for 1-2 minutes, stirring frequently, until browned. Season with salt and pepper.
If using provolone cheese, lay the slices over the steak in the skillet and let them melt. If using Cheez Whiz, add it to the steak and stir until melted and combined.
While the cheese melts, lightly toast or warm the hoagie rolls.
Spoon the steak and cheese mixture into the prepared rolls. Add the cooked onions and peppers back into the sandwich.
Serve immediately.
Notes
For the most authentic flavor, use Cheez Whiz. Provolone is also a popular choice.
Using deli-shaved beef is a convenient alternative if you don’t want to slice your own steak.
Amoroso rolls are traditional, but any soft hoagie roll will work.
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