4 tablespoons oil or butter, divided
1 small onion, sliced into half-moons
1 cup sliced mushrooms
2 pounds steak, thinly sliced (such as ribeye)
8 slices provolone cheese
8 slider buns
cheese sauce, optional
Heat 2 tablespoons of oil or butter in a griddle or sauté pan over medium heat. Add the onions and cook until softened.
Add the mushrooms and another 2 tablespoons of oil. Sauté with the onions for 2 or 3 minutes.
Add the sliced steak. Use a spatula to break apart the meat as it cooks, mixing with the mushrooms and onions.
When all the steak has browned, lower the heat and lay the slices of provolone down evenly over the steak, mushrooms and onions.
When the provolone is half melted, turn off the heat. The residual heat will keep melting the cheese.