Makes 12 deviled eggs; can be multiplied.
6 large eggs
2-1/2 Tbsp mayonnaise
Zest of 1 lemon
Juice of half a lemon
1/2 tsp minced capers
2 tsp minced fresh flat-leaf parsley
1/8 tsp kosher salt
In a medium saucepan, place the eggs, and cover with water by one inch. Bring to a boil over high heat. As soon as the water boils, cover the pot and remove it from the heat. Let sit for 12 minutes. Then, drain the hot water, rinse the eggs under cold water, and shell the eggs. Set on a plate and place in the refrigerator for an hour or more.
With a very sharp knife, cut eggs in half lengthwise; gently remove the yolks and place them in a small bowl. (Tip: if the egg white halves are rolling around on your plate, slice a tiny bit off the outside of the bottoms, to make them sit up straight.)
Add the remaining ingredients to the yolks and mash together with a rubber spatula until smooth. Taste, and add more salt if needed.
Transfer the yolk mixture to a pastry bag fitted with a plain or star tip. Pipe the filling into the egg-white halves, swirling upward as you go. (You can also use a plastic zip-loc bag. Push the egg mixture down into one corner. Snip the corner with scissors, and pipe filling into the egg whites.)
Serve immediately, or cover and refrigerate until ready to serve.