In a mixing bowl, combine the salt, black pepper, dried parsley, dried dill, dried chives, garlic powder, onion powder, and minced dried onion.
Add the mayo, sour cream, and buttermilk to the bowl.
Whisk all the ingredients together until the mixture is smooth and well combined.
Taste and adjust seasoning if necessary.
Refrigerate the dressing for at least 30 minutes before serving to allow the flavors to meld.
