Preheat your oven to 350°F (175°C). Gather all your ingredients and equipment.

In a skillet over medium heat, add olive oil and warm it for about 1 minute. Sauté thinly sliced green bell pepper, onion, and mushrooms for around 5 minutes until tender.

Stir in the thinly sliced roast beef, garlic powder, salt, and pepper. Cook for an additional 3-5 minutes until the beef is heated through.

Lay out the provolone cheese slices on a clean surface. Spoon the beef and vegetable mixture onto each slice and roll up carefully, placing seam-side down in a greased baking dish.

Bake the roll ups for about 10 minutes, until the cheese is melted and bubbly with golden-brown edges.

Let the roll ups rest for a few minutes before serving to allow the cheese to settle.

Serve warm with a fresh salad or sugar-free dipping sauce.