Add to Blender Jar: Add everything except chopped pickled jalapeños to a small blender jar or food processor.
Blend the Base: Blend on high speed for 20–30 seconds until the mixture is completely smooth and uniform.No blender? Add all the ingredients (except the jalapeños) to a medium bowl and whisk vigorously for 1–2 minutes until completely smooth. Make sure there are no visible spice clumps.
Fold in the Jalapeños: Transfer the blended sauce to a bowl or jar. Add the roughly chopped pickled jalapeños and stir them in by hand (spoon).
Rest and Serve: Cover and refrigerate for at least 30 minutes before serving. The spices bloom and the sauce thickens slightly as it chills. Taste after resting and adjust: more brine for tang, more cayenne for heat, a pinch more sugar if it tastes too sharp.
Notes
Rest before serving — minimum 30 minutes, overnight is better. In a no-cook sauce like this, the spice powders need time to fully hydrate and bloom in the mayo and sour cream base.
Taste after resting, not immediately after blending. The sauce tastes quite sharp and a little harsh right after blending because the spices haven't integrated yet. Always taste after the resting period to judge the final flavor balance.