01 - Place potatoes in a large pot and cover with cold, salted water. Bring to a boil, then reduce heat and simmer for 10 to 12 minutes until just fork-tender. Avoid overcooking.
02 - Drain potatoes and spread on a baking sheet to cool for 10 minutes.
03 - In a large bowl, whisk together mayonnaise, sour cream, Dijon mustard, apple cider vinegar, sugar, salt, and black pepper until smooth.
04 - Add cooled potatoes, celery, red onion, dill, and chives if desired to the dressing. Gently toss to coat evenly.
05 - Taste and adjust seasoning as needed. Cover and refrigerate for at least 1 hour to allow flavors to meld.
06 - Before serving, garnish with additional fresh dill sprigs.