In a small pot, add liver piece(s), onion, butter, water, salt, and pepper. 

Bring to a boil, then cover and reduce to medium low. 

Cook for approximately 7-10 minutes or until water is almost completely evaporated. Check and stir every couple of minutes. 

When water is pretty much gone, remove from the heat and let cool.

Use a blender, food processor, or mortar and pestle to blend the liver and onion into a paste, OR mince very, very finely with a knife, scraping the resulting mash back and forth with the flat of the blade to mash it further. Set aside. 

Meanwhile, bring a large pot of water to a roiling boil. 

Gently add the room temp eggs with a spoon and set a timer for 10 minutes. 

Once 10 minutes is up, dump out the hot water and run cold water over the eggs to stop them from cooking. 

Peel the eggs, then cut them in half. 

Using a little spoon, gently scoop out the yolks and move them to a bowl.

Mash the yolks with a fork, then add the horseradish, mayo, onion, and liver paste. Mix very well. 

Either spoon the resulting liver-yolk mixture back into the empty egg whites, OR put the paste into a small ziplock bag and snip the bottom corner off the bag with scissors. Seal the bag, then squeeze the bag with the cut corner hovering over the egg whites. “Pipe” out the paste evenly into each egg white.

You may end up with a little bit left over, enjoy this on bread as a snack!

Garnish the eggs with a dusting of paprika and some fresh herbs. You could garnish with sliced black olives, cayenne, sliced pickles, green onions, or sliced cherry tomatoes as well. Enjoy!