A recipe from “Berømte Retter” (Famous Dishes) published by Ernst G Mortensen in 1970
Dried cod is a favourite everywhere in Portugal, but especially along the river Douro and Oporto, where the fish is called "O fiel amigo", the faithful friend who never fail you. A girl’s chances of marriage depends on whether she knows at least ten different ways to cook bacalao.
One can follow the dried fish trade back to the 16th -17th century. When the English ships brought dried fish to the ports of northern Portugal they took wines from the upper regions of the Duoro as payment. This wine trade became increasingly important and is the beginning of the English port wine culture. Towards the end of the 17th century came the wars with France, which led, among other things, to the English being unable to get hold of French wines. English wine merchants started settling at the mouth of the Duoro river in the small town of Vila Nova da Gaia near Oporto, where their descendants still live.