Place Large Egg (12) in a large pot of water. Make sure the tops of the eggs are covered in water. Bring water to a boil and boil eggs for 20 minutes.
Remove eggs from the heat and drain water out of the pot. Fill the pot with cold tap water. Let sit for 5 minutes so the eggs cool.
Peel eggs and rinse with cold water to wash off small shell pieces.
Cut eggs in half, putting yellow yolks into a medium-sized mixing bowl. Put egg whites to the side for filling later.
Mash eggs finely with a fork. Mix in Salt (1/4 teaspoon), Ground Black Pepper (1/2 teaspoon), and Apple Cider Vinegar (1 tablespoon).
Mix in Mayonnaise (1/2 cup), Horseradish (2 teaspoon), and Yellow Mustard (2 tablespoon) until smooth.
Fill egg whites with yolk mixture. Refrigerate until ready to serve, covering with a plastic cover to keep air out. Enjoy!