Stoccafisso

Stockfish is North Atlantic cod hung on outdoor wooden racks and dehydrated by cold wind and low arctic sun. No salt, no smoke, no heat. It loses seventy to eighty per cent of its weight and turns rigid, feather-light and leather-coloured: a fish you can hold by the tail like a board.

The name comes from the Norse and Dutch stokvis, 'stick fish', after the poles it hangs from; Italian turned it into stoccafisso.

Technically it is remarkable. With no water and no salt in it, it keeps for years at room temperature and retains almost the full protein profile of fresh fish: over eighty per cent protein by dry weight. Before canning and industrial refrigeration, it was the most transportable protein in Europe, and it is why a mountain village in Calabria ended up building its cuisine around an arctic fish.

Once rehydrated and cooked, stockfish is softer, more fibrous and far more delicate than salt cod. It does not flake into wide leaves; it separates into fine threads, which is exactly why it can be beaten into a white cream with olive oil, as the Venetians do, and why salt cod cannot.

The flavour is concentrated cod with a distinctive dried, faintly cheesy depth from the months of air-curing: savoury rather than salty, since no salt was ever added. Anything salty in the finished dish came from the anchovies, the cheese or the cook.

Dried and unsoaked it smells strong, sweet and slightly barnyard; that is normal. Ammonia is not. If it stings the nose, the fish has gone and no amount of soaking will bring it back.

Soaking is long and there is no way around it. First beat the dried fish with a mallet or a rolling pin to break up the fibres: noisy, necessary, and something most fishmongers will do for you. Then submerge it in plenty of cold water in the refrigerator for three to four days, changing the water morning and evening. It will roughly triple in weight.

Unlike salt cod, you are not removing anything; you are putting water back. So judge readiness by texture, not by taste: when the flesh yields under a finger and is evenly springy all through, it is ready.

The signature dish is baccalà alla vicentina. Flour the pieces, lay them in a heavy pot on a bed of slow-cooked onion with anchovies and parsley, cover with equal parts olive oil and milk, and cook for four to five hours on the lowest possible heat without ever stirring. The dialect word for the required simmer is pipare: the surface should blow the occasional bubble, like a pipe. Serve it with white polenta.

Venetian baccalà mantecato is the other great preparation: stockfish poached, then beaten for twenty minutes with extra virgin olive oil until it becomes a pale, glossy cream, served on grilled polenta. In Calabria, stocco is stewed with potatoes, tomato, olives and chilli.

Dried, it is one of the most durable foods in an Italian kitchen, because there is almost no water left in it. A whole or cut piece keeps for a year or more hung or laid flat in a cool, dry, airy place, wrapped in paper or cloth, never in a sealed plastic bag, which holds in whatever moisture the fish gives up. It does not need the fridge in that state. The pack or the fishmonger carries the date, and that is the reference.

Once soaked, everything reverses. The rehydrated fish has gone back to roughly three times its dried weight and behaves like fresh fish: keep it in the fridge, covered in clean cold water, change that water daily, and use it inside two days. Over the drying year the flesh continues to lose the last of its moisture, going harder and more amber, and the surface oils oxidise slowly, which is why the trade grades and sells within a season. Soaked stockfish freezes usefully in portions, drained and wrapped tight, for two to three months.

Dried stockfish is unmistakable once you have seen it: a flat, board hard plank of fish, pale straw to grey beige, so rigid it will not bend, and surprisingly light for its size. There is no salt crust and no salt crystals anywhere on it, which is the whole difference from salt cod. Salt cod is whiter, visibly salted, heavier and pliable. In the Veneto the two get tangled because the local name for stockfish is baccalà, which everywhere else in Italy means the salted one.

Grade is printed on the label and matters. Italian buyers take almost the whole Lofoten production and grade it themselves: Ragno is the top tier, thick, pale and even, and it is what Vicenza and Naples pay for. Look for Norway or Lofoten as origin and Gadus morhua as the species, since Arctic pollock dried the same way is thinner and cheaper. Fishmongers abroad sometimes sell it already soaked, sitting in cold water, and that version is priced per pound of wet weight. Dried, expect $30 to $60 a pound; soaked, roughly a third of that.

In the US, Italian importers and specialist fishmongers sell dried stockfish at roughly 25 to 45 dollars per pound, and African and Caribbean grocers frequently carry the same Norwegian product for considerably less. Choose thick body pieces over heads and tails. Some Italian delis in New York and New Jersey will sell it pre-soaked around Christmas.

In the UK, Norwegian and Italian importers ship it, and African food shops are the most reliable high-street source, generally 30 to 60 pounds per kilo dried. Very few British fishmongers stock it as a matter of course.

The price looks alarming until you account for yield: a kilo of dry stockfish becomes about three kilos of cooked-ready fish, or eight to ten portions, so the real cost per serving lands close to a decent fresh fish. Four hundred grams of dry fish feeds four people.

Judge quality by thickness, colour and smell. Uniform straw to pale leather colour, dry and matte on the surface, rigid but not crumbling, with a strong, clean, faintly sweet smell. Brown or greenish patches, an oily film, or any hint of ammonia mean the fish is finished.

Vicenza and its province, where baccalà alla vicentina is a civic institution. Sandrigo, home of the confraternity that codified the recipe, holds a festival every September; in Vicenza itself the dish is on osteria menus year-round, served with white polenta.

Venice, for baccalà mantecato. In the bacari of Cannaregio and San Polo and around the Rialto it comes as a cicchetto on a slice of grilled polenta for two or three euro. It is the quickest possible education in what this fish becomes after twenty minutes of beating with olive oil.

Calabria is the surprise. Mammola, a mountain town in the Aspromonte in the province of Reggio Calabria, built its cuisine on stockfish, holds a summer festival for it, and has restaurants whose menus are largely one ingredient. Nearby Cittanova has a parallel tradition. A landlocked Calabrian village living off arctic cod explains more about pre-refrigeration food history than any museum.

Genoa and Liguria have their own version, stoccafisso accomodato, with olives, pine nuts and potatoes.