1/4 cup olive oil, divided, plus more for grilling
1 medium zucchini, cut lengthwise into thick slices
1 bell pepper, halved, stemmed, and seeded
1 small red onion, halved
1 small eggplant, cut lengthwise into thick slices
4 large tomatoes, cut crosswise into thick slices
3 to 4 tablespoons balsamic vinegar (preferably white)
1/4 cup roughly chopped fresh parsley
In a medium pot of boiling salted water, cook pasta according to package instructions. Reserve 1 cup pasta water, then drain and return to pot.
Heat a grill or grill pan to medium-high; clean and lightly oil hot grill. Working in batches if necessary, lightly brush vegetables with 2 tablespoons oil, season with salt and pepper, and grill, turning occasionally, until browned and tender. Transfer vegetables to a cutting board and let cool slightly.
Roughly chop vegetables, then add to pasta, along with 2 tablespoons oil and vinegar to taste. If necessary, add pasta water to create a light sauce that coats pasta. Season with salt and pepper, sprinkle with parsley, and serve.