Add the buttermilk and sour cream to a mason jar, cruet, or small bowl.
Add the parsley, onion powder, garlic powder, dill, basil, sea salt, dried mustard, and coarse ground pepper.
Stir until thoroughly combined.
Seal the container and store the ranch dressing in the refrigerator.
Notes
This recipe makes a thick and creamy ranch dressing. If you want your dressing to be thinner, add a little buttermilk or whole milk 1 tablespoon at a time until it reaches the desired consistency.