Bacalhau

Portugal eats more cod per head than anywhere, and none of it comes from Portuguese water - cod is a cold northern fish, and the connection began in the fifteenth century when Portuguese boats reached the Newfoundland banks, salted the catch to preserve it for the voyage, and found that the resulting product suited a Catholic country with many fast days and a hot climate without refrigeration. It is called o fiel amigo, the faithful friend. The claim is that there are three hundred and sixty-five recipes, or a thousand, depending on who is saying it; the ones that matter are bacalhau à Brás, shredded with straw potatoes and egg, à Gomes de Sá with potato, onion and olives, com natas in cream, and simply boiled with potatoes, cabbage, egg and oil, which is the Christmas Eve meal in most households. It must be soaked for a day or more before cooking.

What you actually see

• The dried fish - stiff salted boards stacked in markets and shops.
• The main preparations - à Brás, Gomes de Sá, com natas, and plain boiled.
• The Christmas Eve dish - boiled cod with potatoes, cabbage and egg in most homes.
• The origin - a northern fish salted on the Newfoundland banks from the 1400s.

When to go

Year-round; Christmas Eve is when it matters most. A meal. Markets sell it dried whole, in pieces or pre-soaked.

Honest expectations

Quality varies enormously - cheap restaurant bacalhau is often thin, overly salty or badly soaked. Buying dried fish means a day or more of soaking with water changes before it is usable. Portions are large. Some cod stocks remain under pressure; sourcing is worth asking about.

Nearby

The Ílhavo maritime museum covers the fleet that caught it; markets everywhere sell it.