In a medium jar with a tight-fitting lid, combine the mayonnaise, buttermilk, and buttermilk powder. 2.
Sprinkle in the salt and a generous amount of freshly ground black pepper. 3.
Add the optional fresh chives or parsley, if using. 4. Secure the lid tightly and shake the jar vigorously for about 30 seconds, or until the dressing is smooth and well combined. 5.
Taste and adjust the seasoning as needed. Use immediately for the freshest flavor, or store in the refrigerator.
Adjust the consistency to your liking. For a thicker, dip-style ranch, reduce the liquid buttermilk to 3/4 cup (960 ml). For a thinner dressing, add more buttermilk, one tablespoon at a time.