• 1 kg (2 lb 4 oz) salt cod, soaked in cold water for 2 days
• 3 tablespoons olive oil, plus extra for shallow-frying
• 4 red onions, halved and thinly sliced
• 2 tablespoons butter
• 3 garlic cloves, crushed
• 250 ml (1 cup) white wine
• 2× 400 g (14 oz) tins crushed tomatoes
• 60 g (½ cup) plain (all-purpose) flour

Drain the fish well and cut into pieces about 4 × 6 cm (1½ × 2½ inches). Pat dry with kitchen paper. Heat the olive oil in a large frying pan and sauté the onions over medium heat for about 5 minutes until they begin to soften. Lower the heat and continue cooking for about 15 minutes, stirring often, until they are soft and richly coloured, then add the butter.

Add the garlic and, when it has coloured a bit, add the wine, season and continue cooking until the wine has evaporated. Add the tomato and a little more salt and pepper and simmer for about 5 minutes, until the tomato has softened a bit. The sauce shouldn’t be too dry or too runny but just loose. Add a few drops of water if it seems dry, or cook for a little longer if it seems too runny.

Meanwhile, heat the extra olive oil in a non-stick frying pan over medium heat. Put the flour on a plate and dust the pieces of fish. Fry the fish in batches for about 8 minutes, or until it is golden on both sides (let it form a bit of a crust before you turn it over as it can be a bit crumbly). Put the cooked pieces on a plate lined with kitchen paper to absorb the oil.

Arrange the fish, skin side down, on top of the tomato and onions in the frying pan and spoon a little of the sauce over it. Heat through for a few minutes, shaking the pan from side to side to distribute the sauce, rather than turning the fish over and breaking it up. Serve immediately with some bread and a side salad. Some people also like this dish at room temperature.