In a large bowl, toss the steak strips with the salt and pepper. Add 2 tablespoons of flour and toss again, making sure the slices are well coated.
Sear the steak, in two batches, over medium-high heat, so that both sides brown, only about 1-2 minutes per side. At this stage we still want the centers pink. Once browned, set aside.
Next, add the onions and mushrooms to the same skillet and brown for a few minutes until the onions are translucent. Now, add the garlic powder, salt, pepper, Worcestershire sauce and the last 2 tablespoons of flour. Stir to ensure the onions are coated with flour.
Add in the beef broth, 1/2 cup at a time, stirring between each addition so that it thickens, until it’s finally fully incorporated to avoid lumps. Allow to thicken and bring to a bubble, then reduce heat to medium low and simmer for 30 minutes.
Add in the peppers in the last 10 minutes of simmering. Add beef after the 30 minutes and let simmer, about 5 minutes, so that it’s heated through.
Serve the stew as is at this point, ladling it into bowls topped with some provolone cheese, or read on to find out how to serve it in bread bowls.