This recipe is all about the molcajete method. Don't forget, guacamole is very much a choose-your-own-adventure kind of dish. Have fun adjusting the amount of lime, salt, cilantro, and heat until you find your own platonic ideal.
3 large avocados
3 tablespoons onion, diced
1 tablespoon minced fresh serrano or jalapeño chile, including seeds
1 teaspoon coarse salt or 3/4 teaspoon fine sea salt
1/4 cup finely chopped cilantro
Juice of 1 or 2 small limes
Begin by grinding a coarse paste of onion, chile, salt and half of the cilantro in a molcajete. The salt will act as an abrasive, assisting you as you grind with the tejolote. (If you like the texture of diced onion, reserve half of the onion to mix in at the end.)
Carefully cut the avocados in half, removing the pits and scooping the flesh into the molcajete. Mix well with the paste and add the rest of the cilantro, giving it a rough mash.
Season to taste with lime juice, extra chile and salt. Garnish with a few totopos (chips) and serve.