Heat the oil in a pan and sear the lamb. Add the mustard seeds, wait for them to pop, then add the fenugreek seeds, fresh chiles, curry leaves, and ginger. Stir and fry for a few minutes.
Using a food processor, chop the onions and add to the pan. Continue to cook for 5 minutes until the onions are light brown and soft, then add the chili powder and turmeric. Put the tomatoes into the food processor, pulse, and add them to the pan. Cook for a couple of minutes, then add 1 or 2 wine glasses of water and the coconut milk. Simmer until the lamb is tender and the sauce has the consistency of double cream, then season carefully with salt.
(c) Jamie Oliver 2002