1. Prepare the curry. Melt the butter in a large, heavy based saucepan. Add the sliced onion, season with salt and pepper and cook over medium low heat for 10-12 minutes, until caramelised. Lift the onions from the saucepan with a slotted spoon and set aside.
2. Increase the heat slightly and cook the lamb in batches until browned. Add the curry paste and stir well to coat the lamb. Stir in the tomatoes and juice, coconut cream, chickpeas and water. Reduce the heat and cook gently for 10-12 minutes, until the lamb is tender. Add the caramelised onions and cook for a further 2-3 minutes. Season with salt and pepper, to taste.
3. While the curry is cooking, prepare the rice. Melt the butter in a saucepan over medium heat. Add the rice and stir to coat in the butter. Add the water and a pinch of salt; bring to the boil. Reduce heat, cover and cook for 15 minutes, or until tender.
4. Garnish the curry with fresh herbs. Serve with buttered rice, yoghurt and poppadums.