Heat coals or gas grill for direct heat. Cut four 18x10-inch pieces of heavy-duty aluminum foil. Spray with cooking spray. Place potatoes and 1 piece corn on each foil piece. Mix remaining ingredients except chives in small bowl; drizzle over potatoes and corn. Turn corn to coat and gently stir potatoes.
Fold foil over potatoes and corn so edges meet. Seal edges, making tight 1/2-inch fold; fold again. Allow space on sides for circulation and expansion.
Cover and grill packets 4 to 6 inches from medium heat 25 to 35 minutes or until potatoes and corn are tender. Place packets on plates. Cut large X across top of each packet; unfold foil. Sprinkle with chives.