In a medium bowl, combine the sour cream, buttermilk, and mayonnaise. Whisk until smooth.
Add the lime juice, minced garlic, chipotle powder, cumin, salt, and black pepper. Whisk again until all ingredients are well combined.
Taste and adjust seasonings as needed. If the dressing is too thick, you can add a little more buttermilk, one tablespoon at a time, until the desired consistency is reached.
For best flavor, cover and refrigerate for at least 30 minutes before serving to allow the flavors to meld.
Notes
This dressing is delicious on salads, as a dip for vegetables or chips, or even as a sauce for tacos and burritos.