Add potatoes, enough water to cover them, salt and 2 tablespoons vinegar to a large saucepan. Bring to a boil, over high heat, then reduce to a simmer and cook until potatoes are tender, about 10 minutes. Drain and transfer to a baking sheet, spreading into one layer.

Season potatoes with the remaining vinegar and salt. Reserve until cooled to room temperature.

Combine mayo, sour cream, relish and Dijon mustard in a large bowl, whisking until smooth. Season with salt and pepper.

Add the chopped celery, red onion and chives, and stir vigorously so everything is coated with the dressing. Then, carefully fold in the potatoes. Taste again and fix seasonings if necessary.

Cover and refrigerate for at least one hour, for the flavors to develop.

When ready to serve, transfer to a serving platter and garnish with the hard boiled eggs, chopped chives and paprika (if using).