Prepare marinade in large shallow bowl. Add eggplant, onions, bell pepper and tomatoes, stirring to coat. Let vegetables marinate 30 minutes or up to 3 hours.
Prepare hot charcoal fire or preheat gas grill on high. Set fine-meshed grill rack on top to heat.
Lightly oil grill topper. Grill vegetables in batches until nicely browned and tender, 2 to 4 minutes per side. Transfer vegetables to baking sheet when they are done. Grill bread alongside vegetables until lightly toasted. Immediately rub warm grilled bread with cut sides of garlic and drizzle with a little olive oil.
Balsamic dressing[]
In small bowl, whisk together dressing ingredients.