Prepare outdoor grill for direct grilling on medium-high.
Heat covered 6-quart pot of water to boiling on high. Add 2 teaspoons salt.
In small bowl, whisk vinegar, oil, and garlic.
Cut onion crosswise into 1/2 inch thick slices. Trim zucchini and eggplant; cut diagonally into 1/2 inch thick slices. Brush half of vinegar mixture on one side of onion, zucchini, eggplant, peppers, and tomatoes.
Grill tomatoes 6 minutes, zucchini and eggplant 10 minutes, and peppers and onion 12 minutes, or until all vegetables are tender and charred, turning over once. Transfer vegetables to cutting board. Cool slightly, then cut into 1/2 inch pieces.
Meanwhile, cook pasta in boiling water as label directs. Drain; return to pot.
Stir mustard into remaining vinegar mixture. Toss with pasta along with parsley, vegetables, 3/4 teaspoon salt, and 1/4 teaspoon black pepper.