Cut the avocados into quarters and remove the peels and pit. Dice, then add to a large mixing bowl.
Halve the garlic clove; remove and discard any green shoots in the center. Mince the garlic.
Dice the onions. Place the diced onions and minced garlic in a small bowl with a little water for a few minutes. This will help the onions and garlic “de-flame” a little and become less potent.
Add all of the other ingredients to the mixing bowl with the avocados. Mash with a fork or whisk. If the avocados are still particularly hard you can pulse them in a food processor.
Drain the water off of the onions and garlic and add to the guacamole mixture. Mix together and serve with tortilla chips.