01 - Preheat oven to 400°F. Arrange pepper halves cut side up in a baking dish. Drizzle with 1 tablespoon olive oil and lightly season with salt and pepper. Bake for 10 minutes to soften.
02 - Heat remaining olive oil in a large skillet over medium heat. Sauté sliced onions and mushrooms for 5–6 minutes until soft. Add minced garlic and cook 1 minute longer.
03 - Add sliced steak to skillet. Cook, stirring, until steak is just browned, about 3–4 minutes. Stir in Worcestershire sauce, salt, and black pepper. Remove skillet from heat.
04 - Remove peppers from oven. Place half a slice of provolone cheese inside each pepper half. Fill evenly with steak mixture, then top each with another slice of provolone.
05 - Return peppers to oven and bake for 15 minutes, or until cheese is melted and bubbly.
06 - Allow to cool for a few minutes before serving to ensure cheese is set.