Yet again, we have another perfect guacamole recipe to work with. This one allows for creativity and flexibility, while keeping all of the basic principles of making guacamole intact.
In a medium-sized bowl, mash 1 avocado with a potato masher until smooth. Dice the other avocado into medium dice and set aside (do not add to the mashed avocado).
Add ½ of the diced onion, 1 tablespoon of lime juice, and salt to taste to a mortar and pestle.
If using the jalapeño, remove the stem and dice. For a spicy guacamole, leave the seeds in, but for a milder one, remove the seeds. Add ½ of the diced jalapeño to the mortar and pestle. If using cilantro and garlic, add ½ of the cilantro and all of the garlic to the mortar and pestle, as well. Grind together the ingredients until a thick paste is formed. Fold in the mashed avocado. Mix well so that all of the ingredients are evenly combined and check for seasonings. Add the diced avocado, the rest of the lime juice, and tomato last, and serve.