Place the cubed potatoes in a large pot and cover with cold water. Add a pinch of salt and bring to a boil over high heat. Reduce heat to medium and simmer for 10–12 minutes, or until potatoes are tender but not mushy. Drain and let cool slightly.

While potatoes cook, prepare the dressing: In a medium bowl, whisk together mayonnaise, Dijon mustard, apple cider vinegar, sugar (if using), garlic powder, salt, and black pepper until smooth.

In a large mixing bowl, combine the warm potatoes, diced celery, red onion, and chopped hard-boiled eggs.

Pour the dressing over the potato mixture and gently fold everything together until evenly coated. Be careful not to break up the potatoes.

Cover and refrigerate for at least 1 hour before serving to allow flavors to meld. Taste and adjust seasoning if needed before serving.