Guacamole

Check the avocados

A ripe avocado gives slightly under gentle thumb pressure at the stem end and the small cap at the stem pops off to show green, not brown, underneath. A hard avocado will not mash; a mushy one tastes flat. Cut each avocado in half lengthwise around the pit, twist the halves apart, and lift the pit out with a spoon.

Scoop and mash

Scoop the flesh into a medium bowl. Add the lime juice and salt right away, before mashing, so the acid coats the surface and slows browning. Mash with a fork or a potato masher until the mixture is mostly smooth with some pea-sized chunks left. Stop before it turns into a paste; guacamole should have texture.

Fold in the onion, chile, and cilantro

Add the onion, chile, cilantro, and the garlic if using. Fold together with the fork until evenly distributed. Rinsing the chopped onion under cold water and patting it dry takes off the raw bite if you find it too sharp.

Add the tomato last

Fold in the diced tomato, if using, with a few gentle strokes so it stays in pieces rather than bleeding into the mix. Seeding the tomato first keeps the guacamole from going watery.

Taste and adjust

Taste with a chip. It should be bright from the lime and clearly salted; if it tastes dull, add another pinch of salt before reaching for more lime. Add more minced chile for heat. Serve right away with tortilla chips.

Storage. Guacamole browns where air touches it. To hold it for a few hours, press plastic wrap directly onto the surface with no air pockets and refrigerate. Scrape off any dark layer before serving. It is best the day it is made and does not freeze well.

Substitutions. Red onion works in place of white. Leave out the chile for a mild version, or add 1/4 teaspoon ground cumin for a warmer flavor.