Heat a griddle, iron skillet, or non-stick pan over medium heat.
Add 3 tablespoons of oil to the pan and sauté the diced onions to desired doneness. Remove and set aside.
Add remaining 3 tablespoons of oil to the pan and quickly sauté the thin meat slices on both sides.
As slices brown quickly, scramble them into smaller pieces using a flat spatula.
Meanwhile, melt the Cheez Whiz in a pot or microwave until smooth.
Place 6 ounces of cooked meat into each roll, pushing meat to one side.
Add sautéed onions and any other desired toppings next to the meat (not on top).
Use a butter knife or chopstick to smear melted Cheez Whiz next to the meat and toppings.
Serve immediately while hot.