Place the cubed potatoes in a large pot and cover them with cold, salted water. Bring to a boil and cook until fork-tender, about 15-20 minutes. Drain thoroughly and let cool for 10 minutes.

While potatoes are cooling, finely chop the hard-boiled eggs (yolks and whites). Set aside.

In a large mixing bowl, whisk together the mayonnaise, yellow mustard, apple cider vinegar, salt, and black pepper until smooth and well combined to create the dressing base.

Gently fold the slightly warm potatoes into the dressing. Use a wooden spoon or spatula to avoid breaking them down too much. The warmth helps the potatoes absorb the flavors.

Add the chopped celery, minced red onion, and sweet pickle relish to the bowled potato mixture. Gently fold in the chopped hard-boiled eggs.

Taste and adjust seasoning, adding more salt or vinegar if desired. Cover the bowl and refrigerate for at least 4 hours, or preferably overnight, to allow the flavors to meld.

Before serving, stir gently once more. Garnish the top with a light sprinkle of paprika for color.