Place potatoes in a large pot and cover with water. Bring to a boil over medium-high heat, then reduce to a simmer until tender, about 15-20 minutes. Drain and let cool.
While potatoes are cooking, peel and chop the hard-boiled eggs.
In a large bowl, whisk together mayonnaise, mustard, apple cider vinegar, sugar, salt, and pepper.
Add cooled potatoes, chopped eggs, celery, and green onions to the bowl with the dressing. Gently mix until everything is well coated.
Sprinkle with paprika and additional green onions for garnish before serving.
Notes
For best flavor, refrigerate the salad for a couple of hours before serving to allow the flavors to meld.