Boil potatoes in their new skins. Peel while hot and mash in a bowl. Add chopped eggs, then sweet relish and onion to taste. Mix dressing ingredients; add only vinegar so sauce is neither too sweet nor too sour. (For a hot, spicy salad, substitute cayenne pepper for black pepper (a little goes a long way). Add to potato mixture. Garnish with egg slices and paprika.