Boil your eggs for 10-12 min. Salt the water while boiling to make it easier to peel the shell. Remove the eggs from the stove and place them in an ice bath to stop the cooking.
Set up your coloring station by placing 1-2 drops of neon gel food coloring or 3-4 drops of liquid food color in the bottom of a small bowl. Add cold water and stir until the color is saturated. Add more or less color depending on the hue you want to achieve.
Once the eggs cool, peel eggs and slice in half. Remove the yolks with a spoon and place them in a bowl and set them aside. Place egg whites into the colored water and let sit 5-10 mins depending on the shade you want to reach.
Remove from the coloring and drain on paper towels cavity side down.
Add your mayo, mustard, and relish in with your yokes. At this point taste the mixture and add salt and pepper to your liking. You don’t want a soupy mixture so be mindful of how much relish and mayo you add. Mix well and place in the fridge.
Once your egg whites have dried (10-15 mins) place them on a serving tray and fill cavities with the yolk mixture. You can do this with a spoon but using a piping bag makes it much easier.