Ceviche

Leche de tigre ('tiger's milk') is more than a marinade — it is the signature element that distinguishes Peruvian ceviche from every other acid-cured fish preparation globally. The blending creates an emulsified, aromatic liquid that penetrates the fish more effectively than straight lime juice. Aggressive pre-seasoning is essential: the fish releases water during curing, diluting the marinade. Season to the point it tastes too sharp and salty alone.

From the canon — Leche de tigre — "tiger's milk" — is simultaneously the curing liquid used in ceviche and, in contemporary Lima cuisine, a standalone sauce served as a shoot… Leche de Tigre: The Science and Art of Ceviche Curing Liquid →

The cut size controls the cure rate. At 2cm, the acid takes 3–5 minutes to penetrate the centre; smaller pieces cure in under 90 seconds and over-cure before assembly is complete. The cut must be decisive and clean — sawing creates torn edges that cure faster than the interior, leading to a rubbery exterior and raw centre. A sharp knife and a cold fish (nearly frozen) make this easier.

Non-reactive means glass, ceramic, or high-quality stainless steel — reactive metals (aluminium, copper) react with citric acid to produce metallic off-notes. The onion is rinsed before use to remove the harshest volatile sulphur compounds. The fish must be submerged — any exposed surface will cure unevenly, creating a mixed-texture result.

The colour change from translucent to opaque is driven by acid denaturing the proteins — the same process as heat cooking, achieved through chemistry rather than temperature. Over-cured fish undergoes excessive protein denaturation: the texture becomes dry, rubbery, and squeaky. The difference between perfect and over-cured is approximately 2 minutes for delicate white fish. Once the fish is opaque throughout, remove from the marinade immediately.

Ceviche is adjusted by taste, not recipe. Lime acidity varies by season and variety; the fish's water content varies by species and freshness; personal tolerance for sourness varies. The correct final balance should trigger immediate salivation — that acute acid response is the sensory signature of great ceviche and the test that separates it from under-seasoned versions.

In Lima, the leftover leche de tigre is considered medicinal — a cure for hangovers and a source of strength, hence 'tiger's milk'. It is often served as a shot alongside the ceviche, or sipped from the bowl after the fish is finished. The three-temperature contrast — cold cured fish, crunchy cancha (room temperature), starchy sweet potato — creates variety that makes the dish more than the sum of its parts.