Place potatoes in large pot and cover with cold water. Until almost tender, about 30 minutes. Drain and cool. Cut potatoes crosswise into 1/2-inch-thick rounds. Whisk remaining ingredients in large bowl to blend. Add potatoes and toss thoroughly to coat. Cover and let stand 1 hour at room temperature.
Prepare barbecue (medium heat). Remove potatoes from marinade and place on grill; reserve marinade. Cook potatoes until golden brown, turning occasionally, about 12 minutes. Transfer to platter. Brush with remaining marinade and serve.
