Peel and dice potatoes into ½ ich cubes.
Place cut potatoes in a bowl of cool water as you cut them to prevent them from turning brown. Set aside.
Add water to a large deep skillet (enough to cover potatoes) and season the water with salt and pepper. (I also added green onion flakes to the water. The water should taste a bit salty like a broth)
Bring water to a boil and with a slotted spoon add potatoes into the water.
Boil just until the potatoes are tender to the bite but still holds its shape. This won't require much time at all. (keep a close eye on them, checking often, because you don't want them to get mushy)
Place potatoes on a plate and refrigerate until cold. (this will help them maintain their shape while stirring in the sauce later)
While potatoes are chilling, boil and peel the eggs.
Place the egg yolks in a large bowl and mash them up.
Dice the egg whites up and place them into the bowl.
Stir in onions, relish, mayo, and mustard.
Season sauce with salt and pepper.
Stir in cooled potatoes until potatoes are coated in the sauce.
Gently mash a few of the potatoes, while stirring to create a creamier, thickened texture.
Taste again and add more salt and pepper if needed.
Place in a casserole dish and garnish the top with paprika and green onion flakes if desired.
Refrigerate for 3 hours or overnight.