To cook the lamb shanks:
- Heat the oven to 160ºC / 140ºC fan / Gas 3.
- Heat the oil in a frying pan and sear the lamb shanks all over until brown, then place them into a deep ovenproof dish.
- Using the same pan, fry the onion, carrot, bay leaf and spices until brown.
- Add the onion and carrot mixture to the lamb shanks in the ovenproof dish, then add the chopped tomatoes. Add enough water to half cover the lamb shanks.
- Cover with tin foil and cook in the oven for 1 hour 30 minutes – 2 hours or until the meat is very tender.
- Remove the shanks from the stock and cover to rest, reserving the juices and stock from the pan.
To make the ragout:
- Put the rinsed lentils and the potatoes in cold water. Bring to the boil, and cook for 15 minutes or until just tender. Drain.
- Heat the oil in a pan and fry the onion, garlic and carrot. When they are soft, add the rogan josh paste, the rest of the can of chopped tomatoes and the cooking liquid to make a smooth sauce.
- Add the lentil mixture and the chickpeas and cook for a further 10 minutes, adding more liquid if necessary.
- Five minutes before serving, add the cherry tomatoes and finish with some fresh coriander.
- Spoon the lentil mixture onto a plate and top with the lamb shanks. Serve with warm naan bread.