In large nonstick skillet, heat oil over medium heat. Add onions and 1 tablespoon of the soy sauce; sauté until onions are soft. Add steak and cook until steak browns slightly; add remaining 1 tablespoon soy sauce and stir to combine. Place cheese on top of steak and stir until melted, mixing steak, onions and cheese together. Scoop steak mixture onto sandwich rolls.
*Freeze steak for easier slicing.