Heat olive oil in a large skillet over medium heat for 1 minute. Carefully add the onion, bell pepper and mushrooms and cook just until tender, approximately 5 minutes.
Stir in the thinly sliced ribeye, garlic, kosher salt and pepper to the hot skillet. Cook until just cooked through, approximately 5 minutes. (Do not overcook the beef).
Spoon cheesesteak mixture into Bibb lettuce cups and immediately top with shredded provolone cheese so cheese melts. Serve and enjoy!