1/2 cup chopped onion
3 stalks celery, diced
3/4 cup mayonnaise (or a little less)
2 T red wine vinegar
2 T yellow mustard
1 t sugar
1 t salt
3/4 t black pepper
Peel and cut the potatoes into small chunks. Place them in a large pot and cover with salted water. Bring to a boil and cook 6-8 minutes until they're firm, yet tender. Drain, and rinse under cold water.
Whisk together the remaining ingredients. Stir in the warm potatoes. Cover and chill, overnight if possible.