Combine zucchini, squash, onion, and bell pepper in a large bowl.
Drizzle with 1 Tbsp olive oil, and toss to coat.
Grill, uncovered, over medium-high heat (350º to 400º) for 10 to 1
2 minutes, turning once, or until just tender.
Whisk together vinegar, salt, and pepper in a large bowl; slowly whisk in remaining 2 Tbsp olive oil.
Add grilled vegetables and basil; toss to coat. Sprinkle with goat cheese just before serving.