01 - Place cubed potatoes in a large pot and cover with cold, salted water. Bring to a boil over medium-high heat. Reduce heat and simmer for 10–12 minutes until fork-tender.
02 - Drain potatoes thoroughly and spread on a baking sheet to cool for 10 minutes, allowing steam to escape and preventing dressing from becoming watery.
03 - In a large mixing bowl, whisk together mayonnaise, sour cream, Dijon mustard, apple cider vinegar, salt, and pepper until completely smooth and well combined.
04 - Add cooled potatoes, celery, red onion, parsley, and chives to the dressing. Gently fold to coat evenly, taking care not to break up the potatoes.
05 - Fold in chopped hard-boiled eggs if using. Taste the salad and adjust salt or pepper as needed to balance flavors.
06 - Cover bowl and refrigerate for at least 1 hour to allow flavors to meld. Salad can be made up to 24 hours in advance.
07 - Garnish with additional fresh herbs before serving if desired. Serve chilled as a side dish for picnics, barbecues, or alongside grilled meats.