Begin with the red onion, jalapeño, and garlic — the components that benefit from sitting briefly before the avocado is added, as the acid from the lime juice you will add later begins to soften their sharpest raw edges during the short rest. Dice the red onion into ¼–⅛ inch cubes. At ¼ inch, the onion is visibly present in each bite of guacamole — a pleasant sharpness alongside the avocado's richness. At ⅛ inch, the onion distributes more finely through the guacamole and contributes its flavour with less textural assertiveness — preferable if you want the avocado to be the primary texture. Both are correct depending on how pronounced you want the onion presence to be. Deseed the jalapeño by slicing it lengthwise and scraping out the seeds and membrane with a small spoon, then dice to ⅛ inch — smaller than the onion so the heat distributes evenly throughout the guacamole rather than concentrating in occasional larger pieces. Peel the garlic and either mince it as finely as possible with a sharp knife or slice it into very thin, delicate slivers. Minced garlic distributes invisibly and contributes its flavour as a background note throughout; sliced garlic produces occasional small pockets of garlic flavour that are more detectable bite-to-bite. Set all three aromatics aside together.

Choose the preparation method based on what texture you are working toward. The mortar and pestle method: halve the avocados, remove the stones, scoop the flesh cleanly from the skins with a large spoon, and add the flesh directly to a large mortar. Use the pestle to pound and crush in broad, circular strokes — working from the outside edges toward the centre and back. This controlled crushing breaks the avocado into an irregular, partly smooth, partly chunky mass where some sections are almost creamy and others retain visible chunks. Stop when the texture looks appealing rather than processing to uniform smoothness. The fork method: place the halved, scooped avocado flesh on a sturdy wooden board or directly in a large bowl. Using a dinner fork, crush the flesh with pressing and folding strokes — press down, fold, press again. The fork tines produce a textured, ridged mash that is naturally irregular and rustic. Both methods produce excellent results; the mortar and pestle is faster for a larger batch. The only incorrect method for guacamole is a food processor or blender — these produce a uniform, airy, pale-green mousse that bears no resemblance to the textured, rich, varied consistency that makes guacamole satisfying.

Transfer the mashed avocado to a large bowl if using the mortar method. Add the diced red onion, diced jalapeño, and minced or sliced garlic. Pour the lime juice over the mixture — the acid immediately begins to coat the avocado surfaces and slow the enzymatic browning that would otherwise begin within minutes. Add the ground cumin, salt, and freshly ground black pepper. Add the chopped cilantro if using — torn or roughly chopped into smaller pieces but not minced into a fine paste, so the cilantro remains visually identifiable and provides textural as well as flavour contrast. Add the green Tabasco if using. Now fold everything together using a large spoon or rubber spatula with deliberate, slow, lifting strokes — scoop from the bottom and fold over the top, rotating the bowl and repeating. The folding motion is specifically chosen over stirring, mixing, or beating: folding preserves the irregular texture of the mashed avocado, keeps the onion and jalapeño pieces intact rather than crushing them smaller, and maintains the rustic, varied character of the guacamole. Aggressive stirring produces a uniform, paste-like consistency where all the structural interest of the preparation is lost. Stop folding when everything is evenly distributed — 8–10 gentle folds is usually sufficient.

Taste the guacamole carefully before the rest period and adjust the seasoning. The correct seasoning balance for guacamole has salt as the most critical variable — under-salted guacamole tastes flat and one-dimensional regardless of the quality of the avocados or the other ingredients. Salt in avocado preparation works differently from many other contexts: it needs to be somewhat bold to penetrate the avocado's high-fat flesh and bring its mild, buttery flavour forward. Add salt in increments, tasting after each addition until the avocado's own character becomes vivid and expressive rather than muted. The lime juice should be perceptible as a background brightness without dominating. The jalapeño should provide warmth rather than sharp spikes. The cumin should be a quiet earthy note rather than a prominent spice flavour. If the guacamole tastes too one-dimensionally rich and fatty, it needs more lime. If it tastes sharp and acidic, it needs more salt. If it tastes flat despite both, it needs more cumin.

Cover the bowl and allow the guacamole to rest at room temperature for 10 minutes before serving. During this rest, the salt draws a small amount of moisture from the onion and jalapeño that distributes through the avocado base, slightly loosening the texture and carrying their flavours into the surrounding guacamole. The lime juice's acidity softens the very sharpest edge of the raw onion and garlic, making them more pleasant and less aggressive. Most importantly, the ground cumin has 10 minutes to bloom in the avocado's natural fat — fat is a far more effective carrier for cumin's fat-soluble aromatic compounds than water, and after 10 minutes of contact with the avocado's rich, fatty flesh, the cumin has distributed and deepened the entire guacamole's flavour in a way that is noticeably more integrated than immediately after combining. Serve immediately after this rest period.

If advance preparation is required, smooth the surface of the guacamole completely flat with the back of a spoon, eliminating all peaks and bumps — these raised areas have more surface exposure to air and will brown first. Squeeze additional lime juice over the entire smooth surface in a thin, even layer — the citric acid inhibits the polyphenol oxidase enzyme responsible for browning. Press a piece of plastic cling film directly onto the guacamole surface, pressing firmly to eliminate every air pocket between the plastic and the guacamole — the contact surface between the guacamole and the film should be airtight with no visible gaps. Alternatively, press the empty avocado stone back into the centre of the guacamole — a traditional technique that works by reducing the surface area exposed to air rather than through any chemical mechanism the stone itself possesses. Refrigerate and use within 4–6 hours for best appearance and flavour.