For the dahl: Put the washed lentils into a large non-reactive saucepan, cover with water and leave to soak for 2-3 hours.
Stir the turmeric into the lentils, then bring the pan to the boil. Add a pinch of salt, reduce the heat and simmer for 30 minutes or until tender, removing any scum from the top as it rises.
Stir in half the butter, then purée the lentils and their liquid to a smooth paste.
In a small pan, combine the remaining butter and oil and heat slowly, add cumin seed and, after 30 seconds, the chopped garlic.
Stir until the garlic is golden brown, adding the chilli half way through. (This mixture is known as the vaghaar).
Add the vaghaar to the puréed dahl and set aside until ready to serve.
For the rice: put the water into a large saucepan with the bay leaves, cardamom and a pinch of salt and bring to the boil.
Stir in the rice, then simmer for 8-10 minutes, until the rice is cooked but still slightly firm. Drain well and keep warm.
Rub the fish fillets with turmeric and a pinch of salt and set aside for 30 minutes. While the fish is marinating, prepare the onions.
. Heat the vegetable oil in a pan over a medium-high heat and add the onions. Stir them gently but frequently until they begin to turn light brown, watching them carefully so that they don’t burn.
. Reduce the heat and keep stirring, breaking up any lumps and making sure the onions stay beneath the oil. As soon as you see the onions turning a darker shade of brown, strain them through a sieve, separating all the strands with a fork. Keep warm.
. In a small bowl, combine the lemon juice, chilli, cumin, coriander, ginger and a pinch of salt to make a paste. Rub the paste onto the fish, sprinkling on more lemon juice or salt if you think it’s necessary.
. Heat a little more oil in a large frying pan, add the fish and cook until well coloured underneath before turning over. (Do not let the oil get too hot or the coating will burn very rapidly.) When cooked, the fish should be crisp outside and delicately soft inside.
. To serve, re-heat the rice and dahl, if necessary, and stir the chopped coriander into the dahl. Serve the dahl on the rice, topped with the fried onions, then place the fish on top, or serve each part of the dish in a separate bowl. Accompany with poppadums.
