Add potatoes to a large pot. Fill the pot with enough cold water to cover the potatoes by 1 inch. Bring the water to a boil. Add a few generous pinches of kosher salt to the water to season the potatoes. Continue to cook until the potatoes are fork tender, about 12-15 minutes.

While the potatoes are cooking, add the mayonnaise, egg yolks, yellow mustard, cider vinegar, and sugar to the bowl of a stand mixer fitted with the whisk attachment, or in a large bowl using a handheld mixer. Beat until smooth and creamy. Season with salt and pepper to taste.

Strain the potatoes and rinse them with cold water to stop the cooking process. Allow the potatoes to rest in the strainer for a few minutes to drain off any excess water.

Transfer the potatoes to the bowl with the mayonnaise mixture. Add the celery and chopped egg whites; fold to combine. Season with salt and pepper to taste. Transfer the potato salad to an airtight container and place in the refrigerator to chill for at least 2 hours. Garnish with scallions and smoked paprika before serving.