4 tablespoon extra-virgin olive oil (EVOO), divided
1 1/2 pounds flank steak
3 tablespoons steak seasoning
1 tablespoon Dijon mustard
2 tablespoons Worcestershire sauce
2 teaspoons hot sauce
4 large yellow onions, thinly sliced
2 large red bell peppers, thinly sliced
3 cloves garlic, chopped
1 tablespoon flour
1 1/2 cups beef stock
Salt and freshly ground black pepper
12 slices provolone cheese
1 large round loaf of crusty bread
Preheat indoor or out door grill to high and oven to 375°F. Heat a medium skillet over medium heat with 2 turns of the pan of EVOO, about 2 tablespoons. Add onions and season with some salt and pepper. Cook, stirring occasionally, for 7-8 minutes. Add the peppers, garlic, mustard, Worcestershire and hot sauce. Continue to cook until peppers are soft and onions are caramel in color, about 5 minutes.
Add the flour and cook for 1 minute, then add the beef stock and simmer until nice and thick. Season the steak with some EVOO and steak seasoning. Transfer the steak to the grill and cook about 5-6 minutes on each side for medium rare. Remove and allow to rest 2-3 minutes. Meanwhile, cut the loaf of bread in half lengthwise. Scoop out some of the bread on the inside and toast in the oven or toaster oven.
Thinly slice the rested flank steak against the grain and add it to the onion and peppers.
Mix to combine. Open the toasted bread loaf and layer the provolone on both sides. Top the provolone with the steak mixture and close the sandwich.
Transfer the cheesesteak to the oven for 2-3 minutes to melt the cheese. Remove from the oven, cut into wedges and serve.