Boil the Eggs: Place the eggs in a pot and cover them with cold water. Bring to a boil over medium heat. Once boiling, cover the pot and remove it from heat. Let the eggs sit for 12 minutes.
Cool the Eggs: After 12 minutes, transfer the eggs to a bowl of ice water to cool for about 5-10 minutes. This makes them easier to peel.
Peel the Eggs: Carefully peel the cooled eggs under running water to help remove the shells without damaging the egg whites.
Prepare the Filling: Slice each egg in half lengthwise and scoop the yolks into a mixing bowl. Add the mayonnaise, Dijon mustard, lemon juice, salt, pepper, and green food coloring. Mash and mix until smooth and creamy.
Pipe the Filling: Using a piping bag or a plastic bag with a corner cut off, fill the egg white halves with the green yolk mixture, creating a peaked effect to resemble a Christmas tree.
Decorate: Use the diced red and yellow bell peppers to create ornaments on the trees. Place pieces in various locations on top of the yolk filling for a festive look. You can also sprinkle chopped chives or parsley for added greenery.
Chill and Serve: Refrigerate the deviled eggs for at least 30 minutes before serving to allow the flavors to meld together.