Preheat the monolith ceramic grill and place the coals on one side to create a direct and indirect zone. On the direct side, the temperature should be set to around 250 degrees Celsius.
Wash and dry the potatoes thoroughly. Place each potato between two opposing bars and cut at regular intervals, but do not cut all the way through so that they look like fans.
Cut the tomatoes and mozzarella into thin slices.
Place the prepared tomato and mozzarella mixture in the incisions in the potatoes. Season with olive oil, salt and pepper.
Place the stuffed potatoes on the indirect side of the grill and close the lid. Cook the potatoes for about 50 minutes until they are soft and the filling has melted.
While the potatoes are cooking, prepare the roast beef. Season with salt to taste.
When the last 15 minutes of the potato cooking time have elapsed, place the roast beef on the direct side of the grill and grill on both sides over a high heat to create a nice crust.
After grilling the roast beef, place it on the indirect side of the grill and monitor the temperature inside. The roast beef is ready to serve when it has reached a core temperature of 54 degrees Celsius.
Serve the fan potatoes with the tomato and mozzarella filling together with the grilled roast beef.
Enjoy your meal!