Place the potatoes in a large pot of salted water. Bring to a boil and cook until tender, about 15-20 minutes. Drain and let cool, then chop into bite-sized pieces.
In a large bowl, whisk together mayonnaise, sour cream, apple cider vinegar, lemon juice, Dijon mustard, salt, and black pepper.
Add the chopped potatoes, celery, red onion, and fresh dill to the dressing.
Mix gently until the potatoes are well coated, and adjust seasoning as needed. Refrigerate for at least 30 minutes before serving.
Serve with green onions sprinkled on top for garnish.