Everyone in our family loves this

Prepare Ingredients: Slice onions, bell pepper, garlic, and steak.
Sauté Vegetables: Heat olive oil in a skillet. Add onions and bell pepper. Cook until softened. Add garlic and mushrooms. Cook until tender.
Add Steak: Add sliced steak to skillet. Cook until heated through.
Prepare Bread: Butter one side of each bread slice. Spread mayo on the other side.
Assemble Sandwich: Place provolone cheese on mayo side of one bread slice. Add steak and vegetable mixture. Top with remaining provolone cheese and the other bread slice (mayo side down).
Cook Sandwich: Heat a skillet over medium heat. Cook sandwich until golden brown and cheese is melted.
Serve: Enjoy immediately!
Optional: Add mushrooms for extra flavor.