Curing salmon is equal parts salt and sugar by weight, applied at 8-10% of the fish weight, pressed onto the flesh and left to work for 24-48 hours under refrigeration. A 1kg fillet receives 80-100g of cure mix — 40-50g fine sea salt, 40-50g white sugar — spread evenly across the flesh side, wrapped tightly, and weighted. This ratio is where the dish lives or dies: too little cure and the fish remains raw and perishable; too much and it becomes unpleasantly dense, dry, and aggressively salty. The technique draws moisture through osmosis, firming texture, concentrating flavour, and creating an environment inhospitable to harmful bacteria. Quality hierarchy: 1) Wild King Salmon (Chinook) or wild Sockeye, cured with precisely measured salt and sugar, laid on a bed of fresh dill and crushed juniper, pressed under even weight for 36-48 hours — the flesh is translucent, deeply coloured, firm enough to slice paper-thin, with a clean oceanic flavour balanced by gentle salinity and sweetness. 2) High-quality farmed Atlantic salmon (Scottish or Norwegian), cured by the same method — fattier, milder, silkier in texture, but lacking the wild fish's mineral complexity. 3) Any salmon cured without proper measurement — salt and sugar thrown on by eye — resulting in uneven cure, mushy spots, and unreliable food safety. The distinction between gravlax and lox matters. Gravlax (Scandinavian) is cured with salt, sugar, dill, and sometimes spirits — a brief cure (24-72 hours) producing a firm, translucent product sliced thin and served with mustard-dill sauce. Lox (from the Yiddish laks) traditionally refers to salmon belly cured in heavy salt brine for weeks — a preservation technique producing intensely salty fish requiring soaking before eating. Modern "lox" sold in delicatessens is usually cold-smoked salmon, not true brine-cured lox. Species selection is foundational. King Salmon (Oncorhynchus tshawytscha) — the largest Pacific species, high fat, deep red-orange flesh, buttery and complex. The premier curing fish. Wild Sockeye (Oncorhynchus nerka) — leaner, intensely red, with an assertive, iron-rich flavour that pairs exceptionally with dill and juniper. Coho (Silver) — moderate fat, milder, a solid middle ground. Farmed Atlantic (Salmo salar) — consistent, mild, forgiving of technique errors because higher fat masks slight over-curing. The dill bed: lay thick dill fronds on the flesh before applying the cure, and another layer on top. Dill is not optional — its aromatic oils (carvone, limonene) penetrate during curing, contributing the signature Scandinavian flavour. Add crushed white peppercorns and crushed juniper berries (Juniperus communis) for a resinous, gin-like note. Texture stages: at 12 hours, the cure has drawn visible liquid and edges begin to firm. At 24 hours, the surface is firm, the centre still soft — a light cure with sashimi-like centre. At 36 hours, the flesh is firm throughout but supple. At 48 hours, the texture is dense and sliceable, with 15-20% moisture loss. Beyond 48 hours, the fish becomes progressively drier and saltier. Sensory tests: the surface should feel firm and slightly tacky, not slimy. Smell should be clean — ocean, dill, salt, with no ammonia. Colour should be deeper and more saturated than raw. When sliced thin on the bias, flesh should be translucent at the edges and evenly coloured.
Weigh everything. Curing by feel is imprecise and risks either under-curing (food safety concern) or over-curing (quality concern). Use a digital scale. The standard ratio — equal parts salt and sugar at 8-10% of fish weight — is a reliable starting point. Adjust from there: more sugar for a milder cure, more salt for a firmer texture and longer preservation. Use the freshest fish available. Curing does not rescue poor-quality fish — it amplifies whatever is already present. Smell the fish before buying: it should smell of the sea, clean and slightly briny, with no ammonia, no fishiness, no sour notes. The flesh should spring back when pressed. Weight and contact are critical. The cure must be in direct contact with the flesh, and the fish must be pressed under weight (a plate with a few cans on top is sufficient). Pressure ensures even contact and speeds moisture extraction. Flip the fish once, halfway through the cure, to ensure both sides cure evenly. Temperature: cure in the refrigerator at 2-4°C/35-39°F. Never at room temperature — the osmotic process works efficiently at refrigerator temperatures, and the cold prevents bacterial growth during the vulnerable first hours before the cure has fully penetrated.
Add a splash of aquavit or vodka to the cure — the alcohol accelerates the penetration of aromatics and contributes a subtle warmth to the finished product. For a variation inspired by Japanese technique, replace sugar with mirin and add a thin layer of kombu under the fish — the glutamates from the kelp amplify the salmon's natural umami. The pellicle (the liquid drawn out during curing) is intensely flavoured — strain it, reduce it, and use it as a seasoning for vinaigrettes or a finishing drizzle. After curing, let the salmon rest uncovered on a rack in the refrigerator for 6-12 hours — this develops a tacky, dry surface (also called a pellicle in smoking terminology) that improves sliceability. Pair cured salmon with traditional accompaniments: mustard-dill sauce (Swedish hovmästarsås), blini, crème fraîche, pickled red onion, and capers. For the sharpest, cleanest slices, use a long, thin-bladed knife (a salmon slicer or yanagiba) and cut in a single drawing motion — never saw back and forth, which tears the cured surface.
Eyeballing the salt and sugar rather than weighing — the most common error, leading to inconsistent results and potential food safety issues. Using iodised table salt, which can impart a metallic, chemical taste — use fine sea salt or kosher salt exclusively. Failing to remove pinbones before curing — they are far more difficult to remove after the flesh has firmed, and pulling them from cured fish tears the delicate surface. Not wrapping tightly enough — air exposure dries the surface unevenly and promotes oxidation, leading to brown patches and off-flavours. Curing for too long — beyond 48 hours, the fish loses its supple, silky quality and becomes chewy and overly salty. Slicing too thick — gravlax should be sliced on the bias at 2-3mm thickness, thin enough to be slightly translucent. Thick slices taste dense and salty rather than delicate. Applying the cure unevenly — mounding it on the centre while neglecting the thin belly and tail edges, which then over-cure and become unpleasantly hard while the thick centre remains under-cured. Using brown sugar, which adds molasses flavour and obscures the clean salmon taste — white granulated sugar is the standard.