Ingredients
1 (1-pound) loaf ciabatta, halved horizontally
½ cup chopped fresh basil
⅓ cup mayonnaise
⅔ ounce Pecorino Romano cheese, grated (⅓ cup)
2 tablespoons capers, rinsed and chopped
1 teaspoon pepper, divided
6 tablespoons extra-virgin olive oil
5 garlic cloves
¼ teaspoon red pepper flakes
1 pound eggplant, sliced into ¼-inch-thick rounds
1 (8-ounce) zucchini, ends removed, halved crosswise, and sliced lengthwise ¼ inch thick
1 red bell pepper, stemmed, seeded, and quartered
½ small red onion, cut into 2 wedges through root end
1 teaspoon plus ⅛ teaspoon table salt, divided
1 tablespoon balsamic vinegar
8 ounces fresh mozzarella cheese, sliced into ¼-inch-thick rounds
Directions
1
Using your hands or metal spoon, hollow out ciabatta by removing inner crumb, leaving ¼-inch border on sides and bottom; set aside. Combine basil, mayonnaise, Pecorino, capers, and ½ teaspoon pepper in bowl; set aside.
2
Combine oil, garlic, and pepper flakes in 1-cup liquid measuring cup. Microwave, uncovered, until bubbling and fragrant, about 90 seconds. Place eggplant, zucchini, bell pepper, and onion on rimmed baking sheet (vegetables will overlap) and brush all over with ¼ cup garlic oil (brush eggplant last, as it will absorb more oil than other vegetables). Sprinkle vegetables with 1 teaspoon salt and remaining ½ teaspoon pepper.
3
FOR A CHARCOAL GRILL: Open bottom vent completely. Light large chimney starter filled with charcoal briquettes (6 quarts). When top coals are partially covered with ash, pour evenly over grill. Set cooking grate in place, cover, and open lid vent completely. Heat grill until hot, about 5 minutes.
4
FOR A GAS GRILL: Turn all burners to high; cover; and heat grill until hot, about 15 minutes. Turn all burners to medium-high.
5
Clean and oil cooking grate. Arrange eggplant and zucchini on grill and cook (covered if using gas) until well-browned and tender, 6 to 9 minutes, flipping as needed for even browning. Transfer eggplant and zucchini to large bowl as each piece finishes cooking. Add 1 tablespoon garlic oil and vinegar and toss to combine; set aside.
6
Arrange bell pepper and onion on now-empty grill and cook (covered if using gas) until well browned and tender, 12 to 16 minutes, flipping as needed for even browning. Transfer bell pepper and onion to cutting board; slice thin, then sprinkle with remaining ⅛ teaspoon salt. (Grill will be used again in step 7.)
7
Brush ciabatta crust with remaining 1 tablespoon garlic oil. Spread mayonnaise mixture inside ciabatta. Build sandwich by layering mozzarella on bottom, followed by eggplant and zucchini, and finally bell pepper and onion. Cap with ciabatta top. Wrap tightly in aluminum foil.
8
Transfer foil-wrapped sandwich to grill and cook, pressing occasionally with spatula, until bread is dark golden brown and charred in spots, 1 to 3 minutes per side (peel back small piece of foil to check bread color). Transfer to cutting board and let foil-wrapped sandwich rest for 5 minutes. Unwrap sandwich, slice, and serve.