In a small bowl, mash the avocado with the cooked egg yolks. Add the lemon juice, salt and pepper. Whip with a small whisk until the mixture is smooth and creamy.
Put the avocado cream into a sandwich or snack bag and snip the end. (Yes. This is a makeshift piping bag. If you have a real one, feel free to use it.) Pipe the avocado cream into each egg half.
Top each egg with a small dollop of harissa and try not to eat them all before your guests arrive!
Notes
I made my own harissa. I will share the recipe with you soon. For now, go ahead and get it from your favorite international market or the ethnic foods aisle at a major supermarket.