1. Wash the lentil in several changes of water and put in a deep saucepan with around 2 pints of water.
2. Stir in the turmeric powder and add the black cardamom pods.
3. Bring to the boil and reduce the heat to simmer. Allow the lentils to cook through and soften. This should take around 30 minutes. Remove the froth that rises to the surface, and top up with water if it boils off too quickly. There should be plenty of water.
4. When the lentils have softened it's time to make the tadka. Gently heat the oil in a frying pan.
5. Add the green caradmom pods, cloves and cinnamon stick. After a minute or so the green cardamom will start to lose its colour and the cloves will begin to swell.
6. Add the cumin seeds and mustard seeds.
7. When they start sizzling, which will only take a minute, stir in the garlic, ginger, chilli and spring onions.
8. Saute for 2 minutes before adding the tomatoes.
9. Stir well and leave to cook for a further minute before removing from the heat and pouring it all into the lentils.
10. Add the salt, sugar, lemon juice and stir through the coriander.
11. Taste and adjust the seasoning.