Grilled Zucchini Caprese Sandwiches
1 medium zucchini, trimmed and cut lengthwise into 6 slices 4 teaspoons extra-virgin olive oil, divided 1 garlic clove, minced 1 1/2 teaspoons balsamic vinegar 1/8 teaspoon kosher salt 1/8 teaspoon black pepper 4 (2-ounce) ciabatta rolls, split and toasted 8 large fresh basil leaves 1 medium tomato, thinly sliced 6 ounces fresh mozzarella cheese, …