Preheat a grill or grill pan to medium-high heat.
Brush both sides of the steak with the olive oil and season generously with salt and pepper.
Brush the grill grates with oil. Place the steak on the grill and grill about 4 minutes. Flip the steak, top with the provolone cheese and sliced tomatoes, season with the fresh oregano, salt and pepper and sprinkle on the mozzarella cheese. Cover and grill for an additional 3 to 4 minutes or until the cheese is melted and bubbling.
Remove from the grill and let rest for 5 minutes before slicing.