Baccalà Fritto alla Napoletana

Baccalà, cod preserved by salting, has been a mainstay of Naples ever since salt cod from the northern seas became the cheap, keepable fish of Catholic fasting days, eaten when meat was forbidden. Fried baccalà is above all the dish of the vigilia, the meatless Christmas Eve dinner, where in Campania it is served alongside fried eel. The stiff, salt-cured fillets must first be soaked in cold water for two to three days, the water changed often, to draw out the salt and swell the flesh back to tenderness. The desalted cod is then cut into pieces, floured and deep-fried until the crust is crisp and the inside flakes. Many Neapolitan cooks finish it in a sauce of tomatoes, Gaeta olives and capers, but on the vigilia it is most often eaten simply fried, hot, with lemon.

A crisp, craggy golden crust over thick, snow-white flakes of cod that pull apart at the fork, gently salty and clean-tasting, the salt tamed by the long soak. A squeeze of lemon lifts it; in the sauced version, sweet tomato, briny olives and sharp capers soak into the crust.

Salting works by osmosis: packed in salt for weeks, the cod loses most of its water and its proteins tighten and cure, which preserves the fish and concentrates its flavour, leaving a salt content above eighteen percent. The long cold-water soak runs that process in reverse, the changed water pulling salt out down its concentration gradient while the flesh slowly reabsorbs water and relaxes back to a tender, flaky texture. Frying then sets a crust: the flour coating and the surface flash their water to steam and brown by the Maillard reaction, sealing a crisp shell while the rehydrated muscle inside cooks just to the point where its fibres separate into clean flakes. Finished in sauce, the porous fried crust drinks up the tomato and brine.