Guacamole — avocado, white onion, fresh chilli, cilantro, lime, salt — is made in a molcajete (volcanic basalt mortar) in traditional Mexican preparation. The molcajete's rough surface breaks the avocado into a specific texture — partially smooth, partially chunky — impossible to replicate with a fork or blender. The basalt's porous surface retains seasoning oils from previous preparations, contributing to the depth of guacamole made in an old molcajete.
- **Avocado ripeness:** The decisive variable. The avocado must yield to gentle pressure at the stem end — not hard (unripe, starchy, no flavour), not mushy (overripe, oxidised flavour). - **The molcajete technique:** Onion, serrano, and salt ground first to a paste — the salt's abrasiveness helps break down the chilli and onion completely. Avocado added and worked to the target texture. - **Lime juice:** Added after the avocado is at the target consistency — not before. Adding lime early oxidises the avocado and changes the texture. - **Cilantro:** Added last, roughly chopped — never blended in. The bruised leaves provide aromatic impact without losing their texture. - **The oxidation issue:** Avocado oxidises rapidly from the moment it is cut. The lime juice slows but does not prevent this. The pit in the bowl: a folk remedy — the pit itself does not prevent oxidation, but it does fill volume and reduce surface area. Pressing plastic wrap directly onto the surface of the guacamole eliminates the air contact that drives oxidation.
Mexico: The Cookbook