2 Tbsp olive oil
2 medium onions, thinly sliced
2 small red and green bell peppers (sliced)
1½ lbs sirloin steak
4 oz sliced American or provolone cheese
4 hero rolls
Heat 1 Tbsp oil in large skillet on medium. Add onions, season with salt and black pepper and cook, covered, stirring occasionally, 8 minutes. Uncover, add bell peppers and cook, stirring occasionally, until very tender, 6 to 8 minutes more; transfer to bowl.
Slice the steak very thinly and season with salt and pepper. Wipe out skillet and heat remaining Tbsp oil on medium-high. Cook steak, tossing occasionally, until browned and cooked through, 3 to 4 minutes.
Lay cheese over steak and cover and cook until cheese melts, about 2 minutes. Remove from heat; gently fold cheese into steak.
Form sandwiches with rolls, steak mixture and pepper-and-onion mixture.