Grilled Portobello Mushrooms with Tomatoes and Fresh Mozzarella

Name: Grilled Portobello Mushrooms with Tomatoes and Fresh Mozzarella
Ingredients: 3 tablespoons olive oil, plus extra for greasing grill pan; 4 large portobello mushrooms (about 5 inches in diameter), stemmed; Salt and freshly ground black pepper; 3 tablespoons extra-virgin olive oil, plus extra for drizzling; 2 cloves garlic, minced; 3 small to medium sized vine ripened tomatoes, cut into 1/2-inch pieces; 8 ounces fresh water-packed mozzarella, drained, cut into 1/2-inch cubes; 1/4 cup chopped fresh basil leaves