First, make the spice mix. Put the coconut, coriander seeds, garlic and curry leaves into a dry frying pan over a medium heat and fry for 5-7 minutes until lightly toasted. Remove from the heat, leave to cool and then grind in a spice grinder until fine. Set aside.
Heat 3 tablespoons of vegetable oil in a heavy-based saucepan over a medium heat. Add the mustard seeds, dried chillies and curry leaves. As they splutter, add the onions and fry for 10-12 minutes until softened and lightly browned. Next, add the tomatoes along with the turmeric and chilli powder. Fry for 5 minutes, mashing the tomatoes lightly with the back of a spoon. At this stage, add the spice paste and stir well. Add the chickpeas, stir well again and cook for 2-3 minutes, then add the water, season with salt, cover and simmer over a low heat for 12 minutes.
Add the coconut milk, cover again and continue to simmer for 7-8 minutes. Finally, add the tamarind paste and stir well. Finish with the garam masala and coriander before serving.
