Place potatoes in cold salted water. Bring to a boil then simmer for 12 to 15 minutes until just tender. Do not overcook.
Drain immediately and sprinkle hot potatoes with apple cider vinegar. Toss gently and cool for 15 to 20 minutes.
Whisk all dressing ingredients together until smooth. Taste and adjust until rich, tangy, and deeply seasoned.
Pour three quarters of the dressing over the warm potatoes. Toss gently to coat every piece.
Add eggs, cheddar, celery, green onions, chives, and optional toppings. Fold through gently.
Taste and adjust seasoning with salt, pepper, and vinegar.
Cover tightly and refrigerate for at least 1 hour. Overnight is strongly recommended.
Before serving stir well and taste again. Refresh with extra mayonnaise, sour cream, or vinegar as needed.
Transfer to a serving bowl. Pile garnishes on top and dust generously with smoked paprika. Serve cold.