Heat a large skillet over medium heat, then add the steak strips and cook, stirring often, just until they've browned- about 6-8 minutes. Transfer the steak to a waiting plate, and set aside.
2 lbs thinly sliced sirloin steak
Add the onion, mushrooms, and garlic to the skillet. Drizzle the olive oil overtop, and sprinkle with steak seasoning. Cook, stirring often, until the vegetables are tender- about 5 minutes.
1 large white onion, 8 oz sliced baby bella mushrooms, 2 tbsp extra virgin olive oil, 1 tbsp minced garlic, 1 1/2 tsp Montreal steak seasoning
Remove the skillet from heat, add the steak back to it, and stir until evenly combined.
Add the bell pepper halves to a 9x13" baking dish, cut side up. Spoon the steak and vegetable mixture into the peppers, dividing it evenly out among them until they're all nice and full.
4 green bell peppers
Top each pepper with a slice of provolone cheese.
8 slices provolone cheese
Bake at 400° for 15 - 20 minutes, or until the peppers have softened and the cheese is melted and golden brown on top.
Carefully remove the hot dish from the oven, and let rest for 5 minutes.
Serve warm and enjoy!