- 2 pounds (about 3-4 medium) zucchini, halved lengthwise
- 4 tablespoons olive oil
- Kosher salt
- Black pepper
- 20 ounces (about 4 cups) cherry tomatoes, halved
- 1/ 2 medium red onion, diced
- 1/ 2 cup fresh basil leaves, torn
- 2 cloves garlic, roughly chopped
- 4 ounces fresh mozzarella cheese, sliced 1/4" thick
- Crushed red pepper flakes, for serving (optional)
- Grated parmesan cheese, for serving (optional)
- Toasted bread or pasta (gluten-free, if necessary), for serving (optional)
Preheat grill or grill pan to medium heat.
Pierce each zucchini half all over with a fork. Brush zucchini halves with olive oil and season to taste with salt and pepper on both sides.
Place a large cast-iron skillet (at least 11”) on grill and preheat for 5 minutes. Add olive oil, red onion, cherry tomatoes, garlic, 3 tablespoons water, and half the torn basil and cook, stirring occasionally, until tomatoes burst and mixture becomes saucy, about 25 minutes. Be sure to crush tomatoes with the back of a spoon as they cook to help them break down.
Meanwhile, place zucchini cut side-down on grill and cook for about 12 minutes on each side, until fork-tender. Once cooked through, set aside on a paper towel-lined plate to absorb excess liquid and turn off the grill. Nestle grilled zucchini into the tomato sauce and spoon some sauce over zucchini. Arrange fresh mozzarella evenly over top and close grill to melt cheese, about 5 minutes.
Serve grilled zucchini parm onto plates and sprinkle with remaining torn basil. Serve with a side of bread, if desired, and eat immediately.