Put eggs in a small pot, cover them with an inch of lukewarm water. Cook on medium heat until it reaches a rolling boil. Immediately turn off the stove and cover the pot. Let it sit for 10 minutes.
Drain the water and fill the pot back up with ice cold water, this stops the eggs from cooking.
Peel the eggs and dice them. Stir in the mayonnaise and the mustard.
Slice the avocado and take out the pit. Fill each half with egg salad and eat with your favorite spoon.