Heat olive oil in a large skillet over medium-high heat.
Add the sliced bell peppers and onions to the skillet. Sauté for 5 to 7 minutes until the vegetables are softened and slightly caramelized.
Stir in the garlic powder, salt, black pepper, and Worcestershire sauce. Cook for an additional 1 minute, then remove from heat.
Preheat your oven to 350°F (175°C) or prepare a clean skillet for searing.
Lay the roast beef slices flat on a clean work surface. If the slices are very thin, double them up for stability.
Place one half-slice of provolone cheese in the center of each beef slice.
Distribute the sautéed pepper and onion mixture evenly on top of the cheese across all slices.
Roll each beef slice tightly around the filling, starting from one end and moving to the other. Secure with a toothpick if necessary.
Place the roll ups on a parchment-lined baking sheet and bake for 8 to 10 minutes, or until the cheese is thoroughly melted and bubbly.
Remove from the oven and serve immediately while warm.