This rich garlicky purée is traditionally made with morue, the French word for salt cod. Salt cod is also sold as bacalao, its Spanish name. Serve warm or cold with toasted slices of baguette.
Soak the cod in cold water for 24–48 hours, changing the water regularly to remove as much salt as possible (see box).
Drain the cod and place in a large saucepan of clean water. Bring to the boil over medium heat, reduce the heat and simmer for 30 minutes. Drain, then cool for 15 minutes.