Combine all ingredients in a jar or other air-tight container, stir, and store covered in the fridge for up to 1 week (or until your buttermilk or sour cream's expiration date).
Notes
-Recipe makes a little over 1 cup of dressing.-For extra freshness, color, or slight flavor change stir in 1 teaspoon of finely cut chives or dill.-Dressing will be thick, add buttermilk (1 teaspoon at a time) to thin and reach your desired consistency.