For the sauce, heat the ghee in a heavy-based saucepan over a medium heat. Add the cardamom and onion and cook until the onion turns a pale gold. Now add the ginger and stir-fry for a few seconds, then add the turmeric, cumin, chilli powder and garam masala and continue to stir-fry for a few minutes, allowing the ghee to separate. If the mixture starts to stick to the pan, add a dash of water and continue to stir-fry for a few more seconds. Add the tomatoes, the saffron and its milk and salt to taste, then stir and simmer for a couple more minutes. Gradually add the yogurt and simmer for a further three to four minutes. Squeeze out the seeds from the cardamom pod and discard the husk. Pour the sauce into a blender and liquidise until smooth.
Now, for the fish, bring the milk, cardamom pods, turmeric and ground cumin to the boil in a heavy-based pan. Poach the fish fillets in this for three minutes on either side, drain, discarding the milk, and transfer to a mixing bowl. Leave to cool. Now remove the cardamom pods and add the potato.<'p>
Blend the onion, ginger and green chilli with 1 tbsp of water to a smooth paste in a liquidiser. Add this to the fish mixture along with all the other ingredients except the oil. Knead well together and form into balls, each the size of a ping-pong ball. (If the mixture is sticky, moisten your hands with water before forming the koftas.)
Heat the oil for deep-frying in a deep, heavy-based pan or wok until it begins to sizzle. Reduce the heat and drop the fish balls into the oil a few at a time, turning them frequently and frying to an even golden brown. Drain on kitchen paper.
Put the koftas into a dish and pour the reheated sauce over. Sprinkle with coriander and almonds and serve.
Recipe courtesy of Reza’s Indian Spice by Reza Mahammad, published by Quadrille (£17.99, hardback). Photos © Martin Poole.