Bengali fish curry

For the marinade: place all of the paste ingredients into a food processor and blend to a smooth purée.

For the fish: rub the fish with the turmeric and salt and set aside for a few minutes. Transfer to a large bowl, then pour over the marinade and mix well to coat the fish in the mixture. Cover with cling film and leave to marinate in the fridge for 1-2 hours.

When ready to cook, remove the fish from the marinade, wiping off any excess with kitchen paper. Set aside, reserving the marinade.

Heat the rapeseed oil in a medium pan until smoking, then add the cassia bark, cloves, cardamom pods, bay leaves and peppercorns. Fry for 1-2 minutes, or until the spices are aromatic and the cardamom has changed colour (keep face and eyes well clear from the pan, as the spices may pop in the heat).

Add the onions and gently fry over a medium low heat for 2-3 minutes, or until softened and golden-brown.

Add the fish and fry for 1-2 minutes on all sides, or until golden-brown all over, then pour in the reserved marinade along with a splash of fish stock and the mustard paste. Cook for 2-3 minutes, then season to taste with sugar and salt. Simmer for a further 1-2 minutes, then turn off the heat and cover the pan with a lid. Leave the fish to cook in the residual heat for 4-5 minutes.

To serve, spoon the fish curry over steamed rice.