There are many devilled egg recipes out there. This is a quick version I tried. They weren't pretty but they sure tasted good.
You will need:
6 hardboiled eggs, shells removed
1/2 Tsp. ground mustard seed or 1-2 Tsp. mustard (the kind you'd put on your sandwich)
1-2 TBS. (per taste) cider or red wine vinegar
1/4 cup (plus 1 TBS. if needed) mayonnaise
Pepper (to taste)
Dash of salt
Cut the eggs in half and reserve the yolks in a small bowl. Arrange the egg halves on a plate. Add the mustard, vinegar, salt, pepper, and some of the mayo to the bowl of egg yolks and mash together with a fork or the back of a tablespoon. Add a little more mayonnaise as needed to make the yolks loose enough to spoon or pipe into your egg halves.
I spooned the yolk mixture into the egg halves, then sprinkled with paprika.
As an alternative, you can use a zip top or flap top sandwich bag, spoon the yolk mixture into the bag, work the mixture to one corner, snip the corner with a clean pair of scissors, and squeeze the mixture on to each egg half in a decorative swirl. That would create a much prettier result than mine.
These were tasty though, and I made them because wanted to see how difficult they were to make (they were easy!) and how they would taste. For a gathering, I would try a little harder to make them look better. For a snack at home with family, these were very good as is.