Boil the Potatoes:
Place potatoes in a large pot, cover with cold water, and add 1 teaspoon salt.
Bring to a boil, reduce heat, and simmer 10–15 minutes, or until potatoes are fork-tender.
Drain and let cool slightly.
Prepare the Eggs:
Place eggs in a saucepan, cover with cold water, bring to a boil, then turn off heat and cover for 10 minutes.
Drain, cool under cold running water, peel, and chop.
Make the Dressing:
In a large bowl, whisk together mayonnaise, mustard, vinegar, sugar, salt, and pepper until smooth.
Combine Ingredients:
Add cooled potatoes, chopped eggs, celery, onion, and relish (if using) to the dressing.
Gently toss until well coated.
Chill & Serve:
Cover and refrigerate at least 1 hour for flavors to meld.
Sprinkle with paprika before serving if desired.