PREHEAT oven to 400°F. Cut potato lengthwise into 8 wedges. Toss potatoes with Italian dressing in bowl. Arrange, cut sides down, on large baking sheet sprayed with cooking spray. Bake 15 min.
MEANWHILE, reserve 2 Tbsp. of the coating mix for potatoes; set aside. Place remaining coating mix on plate. Spread one side of fish fillets with half of the Miracle Whip . Dip fish in coating mix. Turn over; brush other side of fish fillets with remaining Miracle Whip. Turn fish over to coat all sides well with coating mix.
REMOVE potatoes from oven; turn over and arrange around outer edges of baking sheet. Place fish in center of baking sheet. Sprinkle reserved 2 Tbsp. coating mix over potatoes. Bake 15 min. or until fish flakes with fork and potatoes are tender.