The word guacamole comes from the Nahuatl words for "avocado" (ahuacatl) and "mixture," or "concoction" (molli)’and what a beautiful "concoction" guacamole is, pale green sparked with the cilantro’s darker green and the red of the tomato.
Grind together the onion, chiles, cilantro, and salt to a paste.
Cut the avocados into halves, remove the pits, and squeeze the flesh out of the shell and mash into the chile base to a textured consistency, it should not be smooth. Stir in all but 1 tablespoon of the tomatoes, onion, and cilantro, adjust seasoning, and top with the remaining chopped tomatoes, onion, and cilantro.
Serve immediately at room temperature (see note above). I do not recommend freezing.