In a skillet over medium heat, cook the thinly sliced beef until just browned, usually around 3-5 minutes.

Add the sliced green bell pepper and onion to the skillet. Sauté for about 4-5 minutes until they are softened.

Carefully slice your French or Italian loaf down the center, creating a pocket. Stuff the beef and vegetable mixture into the loaf.

Sprinkle the shredded provolone cheese over the stuffed mixture, covering it generously.

Combine melted butter with minced garlic. Brush this mixture generously over the top of your filled loaf.

Cover the stuffed loaf with foil and bake at 350°F for about 20 minutes. Remove the foil and bake for an additional 10 minutes.