Grandpa used to grate horseradish for Grandma's horseradish sauce. All of the men would sit around eating, crying and proclaiming how wonderful it was. To little Wayne, this was a mystery.
Quarter the potatoes and boil until just cooked. Drain and rinse. Mix together mayonnaise, mustard, horseradish, and pickle juice. Transfer still warm potatoes to mixing bowl and blend in dressing. Chop pickles and onions to 1/4-inch dice and add. Season with salt and pepper. Serve chilled.