1. Preheat oven or barbecue (for indirect cooking) to 160-180 ºC.
2. Submerge the grill paper and string in water, wine, beer or juice for 10-40 minutes.
3. Grease the front of the grill paper with oil and place the cheese in the middle of the sheet along the grain of the wood. Drizzle with oil on top, add some salt and black pepper.
4. Wrap a sheet over the food, overlapping the edges at the top, and tie the roll with damp twine. Foil the ends so that the melted cheese does not flow out of the roll.
5. Place the roll on a baking sheet and place in the oven. If you are using a barbecue, place the roll on the wire rack and close the lid.
Bake for 10-20 minutes.
6. In a bowl, combine tomatoes, cut in half, with 1/4 teaspoon. salt, 1/4 tsp. pepper, 1 tbsp. l. olive oil and basil leaves, torn into pieces.
7. Transfer the rolls to a serving platter. Remove the foil and unfold. Spread the tomato mixture on top and invite guests.