The order in which you cut and add the components to the bowl is as important as how you cut them. Begin with the red onion, then the jalapeño, then the mango, then the herbs — and save the avocado for absolute last, cutting it immediately before dressing and tossing. This sequence is not arbitrary: each ingredient is ordered by how quickly it deteriorates once cut and exposed to air. Red onion and jalapeño are the most stable — they can sit cut on the board for ten minutes without any quality change. Mango is also stable but should not sit long as its juice begins to collect on the board and the surfaces start to oxidize slightly. Herbs are somewhat fragile when cut and should be prepared close to the moment of combining. Avocado is the most fragile of all — its flesh begins browning through enzymatic oxidation within minutes of being exposed to air. Cutting it last and moving directly from board to bowl minimises the window of air exposure before the lime juice in the dressing — which slows the oxidation reaction — coats the flesh. A salsa where the avocado was cut first and sat waiting while everything else was prepared often looks brown and uninviting before it even reaches the table.

Peel the red onion and dice it into ⅛–¼ inch cubes — approximately 3–6mm per side. The smaller end of this range, ⅛ inch, produces onion pieces that distribute invisibly throughout the salsa, contributing their sweet-sharp flavour in every bite without any single piece asserting itself as a dominant element. The larger end, ¼ inch, produces slightly more presence — individual onion bites that are discernible among the mango and avocado. Both are correct depending on preference: finer for a smoother, more cohesive result; slightly larger for more textural contrast. Red onion is used rather than white or sweet onion for its sharper, slightly more pungent allium character and its vivid purple-pink colour that adds visual contrast against the orange-yellow mango and green avocado. Transfer the diced onion directly to the serving bowl.

Slice the jalapeño in half lengthwise. Use a small spoon or the tip of a knife to scrape out all the seeds and the white membrane cleanly — the membrane contains the highest capsaicin concentration and is the source of the most intense, concentrated heat. Once deseeded, dice the jalapeño into genuinely small pieces — ⅛ inch cubes, approximately 3mm per side. This fine dice is specifically important for a salsa where the heat should be an even background warmth distributed throughout every bite rather than an occasional intense encounter with a larger chili piece. A ⅛ inch jalapeño cube provides a flavour presence — slightly vegetal, gently warm — without any single bite delivering a disproportionate spike of heat. The green jalapeño specifically provides a fresh, slightly grassy heat that is different in character from the red jalapeño's more fruity profile — it is the correct choice for a salsa that emphasises brightness and freshness over depth and complexity. Add to the bowl with the onion.

Peel both mangos and cut the flesh from around the flat central stone. The easiest technique: stand the mango upright and slice down through the flesh on either side of the stone, producing two large mango cheeks and two smaller side pieces. Score the flesh of each cheek in a crosshatch pattern — parallel cuts approximately ¼ inch apart in both directions — then invert the cheek and slice the scored cubes away from the skin. This technique produces clean, uniform mango cubes quickly and with minimal waste. Aim for pieces roughly ½ inch — slightly larger than the onion and jalapeño cubes. The mango cubes should be substantial enough to provide their own identity in the salsa — a sweet, juicy, tropical presence — rather than disappearing into the other components at a similar small size. Add to the bowl.

Combine the cilantro and parsley in a pile on the cutting board — the ⅔ cilantro to ⅓ parsley ratio is a deliberate formula that produces a herb character that is primarily cilantro-forward with its citrusy, floral, distinctly Mexican identity, while the parsley provides a clean, slightly more neutral herbal background that prevents the cilantro from tipping into overwhelming intensity. Chop together using a rocking knife motion until finely but not completely uniform — the herbs should be visibly chopped and aromatic rather than a fine paste. Add to the bowl. The cilantro-parsley combination also provides a practical benefit: for anyone who finds pure cilantro too dominant, the parsley dilutes it to a more accessible level without removing it. For cilantro lovers, the ratio can be shifted toward all cilantro without any other adjustment.

In a small jar or bowl, combine the lime juice, lime zest, olive oil, salt, black pepper, and the optional green Tabasco. The green Tabasco is listed as optional but is worth including — it is made from jalapeños and has a fresh, tangy, moderately spicy character that is specifically and naturally suited to fresh fruit salsas in a way that red Tabasco's more vinegary, earthier profile is not. It adds an extra acid-heat dimension that makes the entire salsa taste more vivid without adding any detectable hot sauce flavour. Whisk or shake until the olive oil and lime juice are as combined as they will get — they will not fully emulsify without a mustard or egg emulsifier, but whisking briefly distributes them well enough to coat the salsa components evenly when tossed.

Immediately before dressing and tossing, halve the avocado, remove the stone, and cut the flesh into cubes while still in the skin — score in a crosshatch pattern with the knife then scoop the cubes out with a large spoon. Cubes approximately ½ inch — the same size as the mango — are ideal for visual and textural balance between the two main fruit components. Add to the bowl with all other prepared ingredients. Pour the dressing over the entire bowl and toss gently using two large spoons or your hands, lifting from the bottom and turning with slow, deliberate strokes. The avocado is the most fragile element — it will break down into a creamy smear if handled aggressively. Toss only enough to distribute the dressing evenly — 6–8 gentle turns. The lime juice in the dressing coats the avocado surfaces immediately on contact, slowing oxidation and preserving the colour.

Cover the bowl loosely and allow the salsa to rest at room temperature for 15 minutes before serving. During this rest, the lime juice continues to soften the raw edge of the red onion's sharpness, the olive oil carries the herb aromatic compounds throughout the bowl, the mango's juice and the lime begin to integrate into a cohesive dressing, and the flavours that were distinct immediately after tossing begin to merge into a unified salsa rather than a collection of separately-dressed ingredients. Taste after the rest period and adjust: more salt if flat, more lime if the brightness needs lifting, more Tabasco if additional heat is wanted. Serve immediately after the rest — this salsa does not improve beyond the 15-minute mark as the avocado will begin browning and the mango will continue releasing juice.