I first came across this recipe in Mexico in 1957, and it seems to be a classic. The perfect guacamole has to be made in a molcajete, a volcanic-rock mortar and pestle, because the flavors intensify when the ingredients are crushed. If you don’t have one, blend the onion, chile, cilantro, and salt, then mash in the avocados just to a rough texture.

MAKES ABOUT 21/2 CUPS

2 tablespoons white onion, finely chopped
4 serrano chiles, finely chopped (seeds and all), or to taste
3 tablespoons cilantro, chopped
Sea salt to taste
3 avocados (about 1 pound)
1/2 cup unskinned tomatoes, finely chopped

TOPPINGS:

1/4 cup tomatoes, finely chopped
1 tablespoon white onion, finely chopped
2 tablespoons cilantro, chopped

Put the onion, chiles, cilantro, and salt into a molcajete and crush to a paste. Cut the avocados in half and, without peeling, remove the pit and squeeze out the flesh. Mash them roughly into the base and mix well. Stir in the tomatoes and sprinkle the surface of the guacamole with the toppings. Serve immediately.

Reprinted with permission from Diana Kennedy’s From My Mexican Kitchen (Clarkson Potter, 2003).