Place the potatoes, whole and with skins, in a large pot with enough cold water to cover by two inches, and a pinch of salt. Bring the water to a boil, and cook the potatoes until just tender when poked with a knife. Start checking around 10-15 minutes. Drain the potatoes and allow to cool.
In a large bowl, combine mayonnaise, sour cream, yellow mustard, mustard powder, salt, black pepper, celery seed, and 2 tablespoons white wine vinegar. Stir in the red onion and celery.
Once the potatoes are partially cooled, after 10 minutes. Peel and cut the potatoes into bite sized pieces. Keep some of the potato skins on, about ¼ of the skins, or to taste. Toss the peeled, chopped potatoes in 1 tablespoon of white wine vinegar, a few pinches of salt, and set aside.
Assemble the salad in the bowl with sauce. Stir in the hard boiled eggs, and then gradually add the fully cooled potatoes. Mix in the parsley if using.
Transfer potato salad to a storage bowl or serving dish, and sprinkle paprika on top.