Peel the eggs, slice them lengthwise, and gently remove the yolks, transferring them to a mixing bowl. Arrange the empty egg whites on a platter, cut-side up and place in the fridge while you make the filling.
Using a fork, mash the yolks until they are completely crumbled. Add the mayonnaise, saurkraut, brine, mustard and mix together until you form a smooth paste. Add sea salt and black pepper, to taste. Mix together until well blended. Set aside. Alternatively for a super smooth filling, mix with an immersion blender or small food processor.
Transfer the egg yolk filling to a plastic bag or piping bag fitted with a tip.
Pipe the yolk filling into each egg white, filling the cups so that the filling mounds a little over the top.
Alternatively, you can scoop the filling into the egg whites with a small spoon.
Garnish with additional sauerkraut, chives and any other toppings you would like.
Notes
Use 1 tablespoon if you want a thicker filling, 2 tablespoons for a bit thinner but with a more prominent taste