I like my meat-to-veggie ratio 3/4 meat to 1/4 veggies, but make it to fit what you like.
Slice onions and peppers in thin strips. Season steak with garlic salt, pepper, steak seasoning, and soy or Worcestershire sauce.
Heat a skillet to medium-high. After it gets hot, add the oil, when the oil begins to ripple add meat and veggies.
Toss and stir mixture cutting meat with two spatulas or knives as you turn. Cook beef to medium-rare. Add cheese over mixture and allow it to melt. Meanwhile toast bun.
Lay toasted bun on top of the mixture and using a large spatula scoop and turn the mixture onto the bun. Serve immediately.