Step 1: Place the cubed Yukon Gold potatoes in a large pot and cover with cold salted water. Bring to a boil, then reduce heat and simmer for 10-15 minutes until fork-tender.
Step 2: Drain the potatoes thoroughly and return them to the warm pot. Drizzle the apple cider vinegar over the hot potatoes and toss gently to combine. Allow them to cool to room temperature.
Step 3: In a medium mixing bowl, whisk together the mayonnaise, yellow mustard, celery seed, salt, and black pepper until smooth.
Step 4: Once potatoes are cool, add the diced celery, minced red onion, and chopped hard-boiled eggs to the pot.
Step 5: Pour the dressing over the potato mixture and use a rubber spatula to gently fold everything together until the potatoes are evenly coated.
Step 6: Stir in the fresh dill. Transfer the salad to a serving bowl, cover tightly, and refrigerate for at least 4 hours before serving to let the flavors meld.