Boil whole potatoes until they are fork tender (12-15 minutes depending on the size of potatoes). You can prewash if you want, or let the boiling water do the work for you. Remove any eyes on them though before cooking.
Drain well and then cool potatoes enough to be able to handle.
While Potatoes are cooling, mix together Hellman’s Organic Mayo, Sour Cream, Horseradish and celery seed together, keep in the fridge until you need it.
Slice potatoes about 1/4 in thick. Do not peel potatoes. It's okay if they fall apart a bit no one will know or see that when you put it all together. We've tried slicing them before boiling and that doesn't work. So stick with slicing them after cooking.
In large bowl start a layer potatoes slices, then salt and paper. Add thin layer of mayo/sour cream mixture. Sprinkle with green onions and parsley. Repeat this layering until bowl is full. Top salad with any leftover mayo mixture, green onions and parsley.