1. Heat olive oil in a large skillet over medium heat. Add ground beef, season with salt and pepper, and cook until browned. Drain excess fat if necessary. 2. Add diced onion, green and red peppers to the skillet and sauté for 4–5 minutes until softened. Stir in garlic and cook for another minute. 3. In a small bowl, whisk together beef broth, ketchup, Worcestershire sauce, and cornstarch. Pour into the skillet and stir well. 4. Simmer the beef mixture for 3–4 minutes until the sauce thickens slightly. Adjust seasoning as needed. 5. Toast hamburger buns lightly, if desired. Spoon the beef mixture onto the bottom halves of the buns. 6. Top each sandwich with a slice of provolone cheese and the top half of the bun. Serve warm.