For the Vinaigrette, mix all ingredients in small bowl with wire whisk until well blended. Set aside.
Brush Romaine lettuce lightly with some of the oil. Toss vegetables with remaining oil, garlic powder and onion powder in large bowl. Place vegetable mixture in grill basket sprayed with non stick cooking spray.
Grill vegetable mixture 10 to 12 minutes or until tender, turning occasionally.
Grill Romaine lettuce over medium heat 3 to 4 minutes or until lightly browned, turning frequently.
Cut Romaine lettuce halves lengthwise in half. Place lettuce on individual plates; top with grilled vegetable mixture. Drizzle with Vinaigrette.