Fill a medium pot halfway with water and bring to a boil over high heat.

Add the eggs to the pot and boil for 10 minutes. Turn heat off, cover pot with lid, and allow eggs to sit in the covered pot for 10 minutes.

Allow eggs to cool and peel.

Add water to a medium bowl, then add some gel food coloring (about ⅛ tsp, and stir. Add eggs to the bowl, making sure that the water covers the eggs. Refrigerate for 2-3 hours

Remove eggs from water, and rinse. They should have a green tint.

Slice eggs in half, putting the yolks in a bowl, the white halves on a plate.

Mash the yolks really well with a fork, then add the mayonnaise, mustard, and a small amount of food coloring (maybe ⅙ of a tsp), and stir until well combined.

Transfer mixture to a piping bag, snip off the end, and pipe mixture into the eggs.

Top with black poppy seeds.

Refrigerate for 1 hour before serving.