1. Preheat oven to 375°F (190°C). Wash and halve bell peppers lengthwise, removing seeds and membranes. Place cut-side up in a 9×13 inch baking dish. Par-cook peppers: add ½ inch water to dish, cover tightly with foil, and bake for 15-20 minutes until slightly softened. Drain water and set aside.

2. While peppers par-cook, heat olive oil and butter in a large skillet over medium-high heat. Add sliced onion and cook 8-10 minutes until softened and translucent, starting to caramelize. Stir in minced garlic and cook 1 minute until fragrant.

3. Push onions and garlic to one side. Add shaved steak to the empty side. Cook, breaking apart, until browned (3-5 minutes). Mix steak with onions and garlic. Pour in beef broth and Worcestershire sauce (if using). Season with salt and pepper. Cook 2-3 minutes until liquid reduces and flavors meld. Remove from heat.

4. Spoon steak mixture evenly into par-cooked pepper halves. Top each with 1-2 slices provolone (or ¼ cup shredded cheese).

5. Bake uncovered for 15-20 minutes, until peppers are fully tender and cheese is melted and bubbly. For extra browning, broil 1-2 minutes (watch carefully). Let rest a few minutes, garnish with parsley if desired, and serve.