In a small bowl or food processor, combine all ingredients except for buttermilk, salt and pepper. Slowly incorporate buttermilk until dressing has a smooth consistency.
Adjust seasoning as necessary.
Store in the refrigerator.
*If you don’t have buttermilk, make your own using 1 tablespoon of lemon juice + 1 scant cup of milk (makes 1 cup buttermilk).