1/4 cup Parmesan-Reggiano cheese (freshly grated)

Salt and pepper to taste

Preheat a grill pan or panini maker to medium heat.

In a large bowl, add the red wine vinegar, dried oregano, fresh oregano, olive oil, salt and pepper, and mix to combine. Add the tomatoes and toss to coat. Set aside.

To make the pesto, start by chopping the garlic in a food processor. Add the basil and pine nuts, and pulse until the basil and nuts are coarsely chopped, then process until finely chopped. With the food processor running, drizzle in the olive oil. The pesto should be slightly chunky and not too wet. Add the grated Parmigiano-Reggiano, and pulse an additional few times until just combined. Season to taste with salt and pepper and set aside.

To build the sandwiches, lay out a top and bottom piece of ciabatta with the insides facing up. Spread pesto on both slices of the bread. On the bottom piece, add a few slices of mozzarella and then the tomato slices. Top with the bread.

Brush the outside of the sandwich with olive oil. Place on preheated panini maker and or grill pan. Cook until golden brown or until the cheese has slightly melted, about 3 to 5 minutes. Continue building the sandwiches with remaining ingredients. Serve at once while they're still warm.

(Mario Batali is the chef behind 25 restaurants, including Eataly, Del Posto and his flagship Greenwich Village enoteca, Babbo.)