Makes 3/4 cup; can be multiplied.
1/2 cup buttermilk (made according to package directions if using powdered)
1 small chipotle pepper in adobo (approx. 1 tsp)
Juice of 1/2 lime
2 Tbsp nonfat plain Greek yogurt
1 Tbsp mayonnaise
1/4 tsp ground cumin or ras-el-hanout
1 small clove garlic, peeled
1 tsp fresh cilantro leaves
Kosher salt and fresh black pepper, to taste
Place all ingredients except salt and pepper in a blender. Process until smooth. Taste, and adjust seasoning with salt and pepper as needed.
Chill for at least 30 minutes, and up to 3 days, to allow the flavors to come together. Serve as a dip with vegetables or pita chips, or as a salad dressing or topping for grilled chicken.