In a large skillet, heat 2 teaspoons of light olive oil over medium heat until shimmering. Carefully add the thinly sliced beef, seasoning it generously with sea salt and ground black pepper. Stir occasionally, cooking for about 4–5 minutes or until the beef is fully browned and cooked through. Once ready, remove the beef from the skillet and keep it warm on a plate.

Using the same skillet, add chopped onion, diced mushrooms, and both diced red and green peppers. Adjust the heat to medium-high and sauté for about 5–7 minutes until the vegetables are tender and the onions are translucent. If needed, drizzle in an additional teaspoon of olive oil to prevent sticking.

With the vegetables ready, return the cooked beef to the skillet, adding in minced garlic for an aromatic boost. Stir everything together until heated through, about 2 minutes.

Spread mayonnaise on one side of each tortilla, if desired. Then, divide the beef and vegetable mixture among the tortillas, placing the filling on one half and topping it with halved provolone cheese slices. Carefully fold the tortillas over, enclosing the filling.

Reheat the skillet and add a small amount of olive oil to promote crispiness. Place one folded quesadilla in the skillet and cook for 3–4 minutes on each side, or until the tortilla is golden brown and the cheese is melted.

Once cooked, remove the quesadilla from the skillet and let it rest for a minute before slicing it into wedges. Serve warm.