Cut the avocados in half, take the seed out and spoon the fruit out of the skin. Inspect for any brown spots and remove if there's any found. Brown spots would promote further browning, reducing the life of our guacamole, not to mention that it isn't that appetizing either.
Place all the ingredients into a mixing bowl.
Mix everything together until getting an even textured sauce. The onion tends to take some time so cutting it into smaller pieces beforehand will reduce the required time.
It's essentially done but it's recommended to stuff the sauce into an airtight container. Preferably something that has a small hole like a tall jam jar. Make sure there are no air pockets left while spooning the guacamole into the jar as it would promote browning and spoiling our efforts quicker than it should. Stick the spoon in and move it up and down until all the holes are worked out.