These Philly Cheesesteak Stuffed Portobello Mushrooms are a delicious and low-carb twist on the classic Philly cheesesteak sandwich. The juicy and flavorful steak is cooked with onions and peppers, then stuffed into meaty portobello mushroom caps. Topped with melted provolone cheese, these stuffed mushrooms are a satisfying and hearty meal that is perfect for a quick weeknight dinner or a tasty appetizer.