Cut the hard boiled eggs in half, wiping the knife with a towel in-between each slice to keep the whites clean. Scoop the yolks into a medium bowl.
Add the mayonnaise (3 tablespoons), the mustard (1 tablespoon), the pickled jalapeño brine (1 tablespoon), and a pinch of kosher salt and black pepper to the bowl. Use an electric hand mixer to combine the yolk mixture until very smooth.
Use a small cookie scoop (or spoon) to refill the whites of the eggs with the yolk mixture, distributing it evenly amongst all 12 egg halves.
Dust with paprika or cayenne pepper, if you want, an extra sprinkling of salt and pepper, and top each egg with a sliced jalapeño pepper.
If you don't like spicy, perhaps jalapeño deviled eggs aren't for you. Just kidding. There are mild pickled jalapeños for less of a kick, and you can use the same ingredients with jarred roasted red peppers or dill pickles- yum!
Don't have an electric hand mixer? Use a fork to mash the yolks with everything else, or put everything in a food processor.
To make in advance, you can store in your fridge already made and assembled a couple of hours in advance. Any longer than that, I recommend mixing up the filling and filling the eggs just before serving. You can do this up to 48 hours in advance.
Need to pack these up in a container to bring with yousomewhere? I recommend a container with egg trays to make sure your eggs stay pretty.