Prepare the Dressing: In a large bowl, mix together mayonnaise, Dijon mustard, apple cider vinegar, sugar, salt, and black pepper until smooth.
Add Mix-Ins: Stir in the chopped boiled eggs, celery, and red onion until evenly combined.
Combine with Potatoes: Gently fold in the cooled potatoes, making sure each piece is coated with the dressing.
Enhance Flavor (Optional): Mix in chopped pickles or fresh herbs like parsley or dill. Sprinkle with paprika if desired.
Chill: Refrigerate the potato salad for at least 1 hour before serving to allow the flavors to meld.
