01 - Place cubed potatoes in a large pot and cover with cold, salted water. Bring to a boil over medium-high heat, then reduce heat and simmer 10-12 minutes until fork-tender.
02 - Drain potatoes thoroughly and spread on a baking sheet to cool for 10 minutes.
03 - In a large mixing bowl, whisk together mayonnaise, sour cream, Dijon mustard, apple cider vinegar, salt, and pepper until completely smooth.
04 - Add cooled potatoes, celery, red onion, parsley, and chives (if using) to the bowl. Gently toss until all ingredients are evenly coated with dressing.
05 - Fold in chopped hard-boiled eggs if using. Taste and adjust salt and pepper as needed.
06 - Cover bowl and refrigerate at least 1 hour to allow flavors to meld. Garnish with additional herbs before serving if desired.