Heat a griddle, iron skillet, or non-stick pan over medium heat. Add 3 tablespoons of soya oil and sauté the diced Spanish onion until softened or caramelized to your preference. Remove the onions and set aside.

Add the remaining 3 tablespoons of oil to the same pan. Add the paper-thin ribeye slices and cook quickly, using a flat spatula to scramble the meat into smaller pieces as it browns.

While the meat cooks, melt the Cheez Whiz in a separate pot or microwave. Prepare the Italian rolls by slicing them lengthwise to create a cradle.

For assembly, place about 6 ounces of the cooked meat into each roll, pushing it to one side. Add the sautéed onions and any optional mushrooms or peppers alongside the meat—not on top. Smear the melted Cheez Whiz next to the meat and toppings using a butter knife or chopstick.