In a medium bowl, with a whisk, beat together 1 tablespoon vinegar, salt, pepper. Add 2 tablespoons olive oil and beat until emulsified. Add the other tablespoon of vinegar and 2 more tablespoons of olive oil and beat until emulsified. Top the mixture with the remaining 2 tablespoons of olive oil. Stir in parsley. Add the garlic clove. Refrigerate until ready to use. Cook pasta per package instructions, drain, rinse with cold water until cool, add to bowl and toss with olive oil and garlic clove. Set aside.
Brush vegetables with olive oil. On a hot grill roast peppers, corn, zucchini and red onion until browned and tender. Remove from grill. Remove kernels from corn and roughly chop remaining vegetables. Toss grilled vegetables and reserved vinaigrette with pasta. Serve at room temperature.