Place the eggs in a single layer in a saucepan and cover with water by at least one inch. Bring the water to a full boil, then cover the pan and remove it from the heat. Let the eggs sit in the hot water for 10 to 12 minutes. Immediately transfer the eggs to a bowl of ice water for at least 5 minutes to stop the cooking process. Once cooled, gently peel the eggs and slice them in half lengthwise. Remove the yolks and place them in a small mixing bowl.
In the bowl with the egg yolks, add the ripe avocado, mayonnaise, Dijon mustard, lime juice, salt, and black pepper. Use a fork to mash the ingredients together until the mixture is very smooth. For an even silkier texture, you can use a small food processor or a handheld blender. The lime juice is essential here as it adds flavor and prevents the avocado from browning too quickly.
Transfer the green yolk mixture into a piping bag fitted with a large star tip. If you do not have a piping bag, a plastic storage bag with the corner snipped off will also work. Pipe the mixture into the hollows of the egg whites using a swirling motion. Start from the bottom and build upward to create a pointed shape that resembles a small evergreen tree.
Carefully place the tiny pieces of diced red bell pepper onto the green mounds to look like Christmas ornaments. Use a small star shaped cutter for the bell pepper if you want a star for the top of each tree. Sprinkle the chopped chives around the base or on top for extra greenery, and add a very light dusting of smoked paprika if you desire a hint of spice. Serve immediately or chill until ready to display.
