Instructions

1. Preheat the oven to 375°F (190°C).
2. Butterfly the flank steak by cutting it horizontally, without cutting all the way through, and open it like a book for easy stuffing.
3. Generously season the inside of the steak with salt, black pepper, and minced garlic, ensuring an even coating for maximum flavor.
4. Spread the tomato sauce evenly over the inside of the steak, covering the meat completely to infuse it with moisture during cooking.
5. Layer the sliced red bell pepper, green bell pepper, and onion on top of the tomato sauce, creating a colorful medley that adds texture and sweetness.
6. Sprinkle the shredded mozzarella cheese and dried oregano over the vegetables for an added burst of flavor.
7. Roll up the steak tightly, securing it with kitchen twine or toothpicks at regular intervals to maintain its shape during cooking.
8. In a large skillet, heat olive oil over medium-high heat. Sear the rolled steak on all sides until browned and caramelized, about 3-4 minutes per side.
9. Transfer the seared steak to a baking dish and cover tightly with aluminum foil to retain moisture and flavor.
10. Bake for 45 minutes, or until the steak is cooked to your desired level of doneness (135°F for medium-rare).
11. Remove the foil and switch the oven to broil. Broil the steak for an additional 5 minutes to melt and brown the cheese, watching carefully to prevent burning.
12. Let the matambre rest for a few minutes before slicing to allow the juices to redistribute for a moist, flavorful result.
13. Slice into rounds and serve hot, accompanied by any remaining tomato sauce on the side for an extra kick.