Chop the onion and bell peppers into small, even-sized pieces for even cooking. Heat a large skillet over medium heat.

Add the chopped vegetables and ground beef to the skillet. Cook, breaking up the beef with a spatula, until the meat is fully browned and the onions are soft, about 5 to 8 minutes. Drain any excess grease if needed.

Sprinkle with salt, pepper, or your favorite beef seasoning to taste. Stir well to evenly coat the meat.

Pour in the beef broth and bring to a gentle simmer. Reduce the heat to low and let it cook for about 5 minutes, stirring occasionally, until most of the liquid has evaporated. This helps keep the mixture juicy but not too runny.

Spread a small amount of butter on the inside of each bun and toast in a skillet or under the broiler until golden. Spoon the meat mixture onto the toasted buns and top each with a slice of provolone or your favorite cheese.

If you want extra melty cheese, place the assembled sandwiches on a baking sheet and broil for 1-2 minutes until gooey. Serve hot and enjoy!