Add the mayonnaise, sour cream, salt and black pepper to a medium size mixing bowl and whisk the ingredients together.
Add the prepared horseradish, apple cider vinegar, and chives to the mixture and mix well until the ingredients are fully incorporated into the sauce.
Store the sauce in a wellsealed container and refirgerate. If time permits store the sauce overnight to give the flavors a chance to build. The sauce is ready to go as soon as its made, but it's going to taste better the next day.