01 - Whisk mayonnaise and sour cream together in a medium bowl until completely smooth and uniform in texture.
02 - Fold in minced jalapeños, jalapeño brine, garlic, cumin, onion powder, salt, and pepper. Mix thoroughly to incorporate all seasonings evenly.
03 - Pour in fresh lime juice and add chopped cilantro. Whisk until fully blended and the mixture takes on a consistent pale green hue.
04 - Cover the bowl tightly with plastic wrap or lid. Refrigerate for at least 1 hour, allowing flavors to marry and develop depth.
05 - Remove from refrigerator and give the sauce a final stir to recombine. Serve chilled as a dipping sauce or condiment.