Light a grill. Brush the rolls with the remaining 2 tablespoons of olive oil and grill over high heat until golden. Add the chicken to the grill, season with salt and pepper and grill over high heat, turning once, until cooked through and lightly charred, about 6 minutes. Place the chicken on the rolls and top with the mozzarella, tomato and basil. Spoon any tomato juices on the top half of the bun, close the sandwiches and serve.