GRILL DIRECTIONS: In small bowl, combine all relish ingredients. Cover; refrigerate while preparing burgers.
Heat grill. In large bowl, combine ground chicken, bread crumbs, yogurt and horseradish; mix well. Shape mixture into 6 patties. When ready to grill, place patties on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 8 to 12 minutes or until no longer pink in center, turning once.
Toast burger buns on grill, cut side down, during last few minutes of cooking time. Place lettuce leaf on bottom half of each bun; top each with burger, relish and top half of bun.