In a medium bowl, whisk together mayonnaise, apple cider vinegar, and lemon juice until smooth
Add horseradish and Dijon mustard; whisk until fully combined
Stir in black pepper, salt, garlic powder, onion powder, and optional cayenne
Taste and adjust seasoning as needed
Cover and refrigerate for at least 30 minutes before serving
Notes
Use full-fat mayonnaise for best textureChill before serving to allow flavors to meldAdd vinegar gradually to control tangKeep cold when serving for optimal flavor