Place all measured ingredients in a medium mixing bowl.
Use a whisk or fork to stir vigorously until the mixture is evenly blended and no visible clumps remain (break up any clumps of buttermilk powder, onion powder, or spices).
If you want an extra-fine, fully uniform powder, sift the mixture through a fine-mesh sieve or pulse it briefly (a few seconds) in a clean spice grinder or food processor.
Transfer the finished mix to an airtight container, seal, and label.
Equipment
Mixing Bowl
Whisk
Fork
Fine Mesh Sieve
Spice grinder
Food Processor
Airtight Container
Notes
1/2 cup sour cream
1/2 cup buttermilk or milk
1 tablespoon dry ranch dressing mix
1/2 cup mayonnaise
1/2 cup milk
1 tablespoon dry ranch dressing mix