Add the sour cream, horseradish, Dijon mustard, and white wine vinegar to a bowl. Whisk until smooth.
Add the garlic powder, black pepper, and a pinch of salt. Stir to combine.
Taste and adjust — add more horseradish for heat or more sour cream to mellow it out.
Refrigerate for at least 15 minutes before serving to let the flavors develop.
Notes
- Prepared horseradish varies in intensity — start with 2 tablespoons and build up. - Store in an airtight jar in the fridge for up to 10 days. - Works as a dip, a spread, or a drizzle on roast beef sandwiches.