Preheat your grill or skillet over medium-high heat.
Season the steak with salt and pepper on both sides.
Add olive oil to the skillet or grill.
Cook the steak for about 4-5 minutes on each side for medium-rare.
Remove the steak from heat and let it rest for 5 minutes.
Sauté the onions and bell peppers in the same skillet until softened.
Slice the steak against the grain into thin strips.
Toast the sandwich rolls lightly on the grill or skillet.
Assemble the sandwich by layering steak, sautéed vegetables, and cheese.
Serve immediately, with optional sauces on the side.