In a large bowl, whisk together mayonnaise, Dijon mustard, apple cider vinegar, salt and black pepper until dressing is smooth. Add the cooked potatoes to the dressing and mix gently.
Mix with celery, red onion, hard-boiled eggs and fresh dill. Cover and refrigerate for at least 1 hour before serving to allow the flavors to blend.
Variations and tips
For a richer salad, add a tablespoon of pickle juice to the dressing. You can also mix it with crumbled bacon or chopped pickles for extra flavor. For a lighter version, replace half of the mayonnaise with Greek yogurt. For a touch of heat, add a pinch of cayenne pepper or chopped jalapeño.
