In a medium bowl combine egg yolks, avocado, lime juice, mayonnaise, parsley, ground mustard and mash using a potato masher or two forks until nice and creamy. Alternatively you can add all the ingredients in a food processor and blend. Season with salt and pepper to taste.
Add mixture into egg whites with a spoon or pastry bag and garnish with a chopped parsley.
Notes
This recipe can also be modified to use only half the eggs yolks and still combine the remaining ingredients for a lighter version.