This is amazing!
4 hoagie rolls, sliced
1/2 green pepper, sliced
1 large white onion, cut in half and sliced thick
8 oz mushrooms, sliced
1.25-1.5 lbs steak (sliced thinly across the grain and then chopped roughly again so they are small pieces)
salt & pepper
3 1/2 Tbsp salted butter
8 slices of Provolone
Prepare 4 sheets of foil and slice the hoagie rolls and set aside. Preheat oven to 250 degrees.
Heat a non-stick skillet with 1 Tbsp butter on medium high heat. Add mushrooms and half of the onions and cook 5-8 minutes or until mushrooms are browned and onions are cooked down. Remove and place on a plate. Add 1/2 Tbsp of butter. Cook remaining onions and bell peppers for 5-8 minutes or until peppers start to brown and blister and the onions are cooked down. Set aside also.
Add 1 Tbsp butter. Season the steak with salt & pepper and add to the skillet. Reduce to medium heat and cook for 2-4 minutes. Add in peppers, mushrooms & onions, cook for 1-2 minutes. Add slices of cheese on top and allow the cheese to melt for 1-2 minutes.
Add the cooked meat & veggies and melted cheese to hoagie rolls. Inside one sheet of foil, roll the hoagie roll tightly and place inside the oven for 10-15 minutes.