Mix olive oil, vinegar, garlic, sugar, salt and black pepper. Place vegetables in a large non-reactive baking dish. Cover with marinade and let sit for 1 hour, turning vegetables every 15 minutes.
Heat grill on high. Grill vegetables until all are marked and cooked through. Remove once browned; do not let vegetables burn. Arrange the vegetables on a platter.
Recipe courtesy of Rocco DiSpirito