Wash and wrap potatoes with aluminum foil and bake (Potatoes can be microwaved if preferred). In a large mixing bowl stir together the chopped onions, grated carrots, sliced celery and relish with the French dressing and Miracle Whip. Add celery seed and black pepper and cover bowl.
Store celery-carrot mixture in refrigerator overnight to allow flavors to marinate. Chill foil wrapped potatoes in refrigerator overnight as well, (this makes the texture of the potato better than boiled or mashed for this recipe).
Next morning, unwrap and peel potatoes and cut into small bite-size cubes. Add celery-carrot mixture and stir until incorporated. Cover and chill in refrigerator for at least one hour before serving.