Slice your peeled, hard boiled eggs lengthwise in half. Pop out the yolks into a small, high sided bowl. Set the white on you plate or tray.
Grate all the yolks, using a small grater into the bowl, until they are all grated and fluffy.
Add mayo, mustard, onion powder, and relish. Stir well to combine.
Add salt and pepper at the end, tasting to get the amount right. They won't need much salt because of the mayo and relish,
Spoon the yolk mixture into a zippie sandwich bag and seal tightly. Snip a corner of the bag off with scissors. "Pipe" the yolk mixture into the egg white cavities, filling them generously. If you end up with leftover yolk, go back and add some to each egg white!
Top each egg with a half of a green olive with pimento. (Totally optional, if you like olives. If you don't, skip it! Another nice garnish is a bit of fresh or dried dill!)
Eat them all up! Enjoy!