There are a few ways to add 'chunks' to guacamole. For chunks of avocado, simply use the back side of a fork instead of a food masher to break the avocado pieces into chunks. Stir the guacamole periodically as you press the avocado. Do this until your desired consistency is reached. Also, if you like tomato and/or onion in your guacamole, feel free to stir in chunks of these to make your guacamole even chunkier.