01 - In a medium bowl, combine sour cream, mayonnaise, prepared horseradish, Dijon mustard, white wine vinegar or lemon juice, salt, and ground black pepper.
02 - Stir thoroughly until the mixture is smooth and all ingredients are evenly incorporated.
03 - Taste the sauce and adjust the horseradish quantity or seasoning to suit your preferred heat level.
04 - For a brighter flavor, fold in chopped fresh chives or parsley.
05 - Cover and refrigerate for at least 30 minutes to allow the flavors to meld together.
06 - Serve chilled alongside roast beef, smoked fish, or grilled vegetables.