Boil potatoes in salted water for 15-20 minutes until fork-tender.
Meanwhile, soak chopped onions in cold water for 10 minutes to reduce sharpness.
Prepare an ice bath; transfer cooked potatoes to it once done.
When potatoes are cool enough to handle, peel and chop into bite-sized pieces.
Toss warm potatoes with vinegar and a light sprinkle of salt.
Whisk together sour cream, mayonnaise, and mustard in a separate bowl.
Add dressing, drained onions, celery, pickles, eggs, and herbs to potatoes.
Gently fold ingredients together, being careful not to mash potatoes.
Season with salt and pepper to taste; refrigerate for at least 30 minutes before serving.
