Make the potato cakes by frying the cumin seeds in a little oil until they crackle, then mixing them with the rest of the ingredients and a good pinch of salt. Form them into 4 round balls, then flatten them in the palms of your hands to create neat cylinders. Set aside in the fridge to firm up

For the lamb, mix together the turmeric, chilli powder, ground coriander, ginger-garlic paste and half of the saffron water with a splash of vegetable oil and a pinch of salt. Use this mixture to coat the pieces of lamb, rubbing it into the flesh, then set aside to marinate while you prepare the sauce

To make the sauce, heat a splash of oil in a heavy-bottomed saucepan over a medium heat. Add the cumin seeds, cinnamon stick and fennel seeds – when they begin to crackle, add the sliced onions and cook, stirring regularly for 20 minutes or until golden brown

Add the ginger-garlic paste and cook for a few minutes until golden, then add the chilli powder, turmeric, coriander, garam masala and a pinch of salt. Cook for 2 minutes, then add the chopped tomatoes and cook for a further 5 minutes, until the oil separates

Add the tomato paste, then cook for another 5 minutes. Remove from the heat, add the remaining saffron water, then remove the cinnamon stick and blitz the mixture into a smooth sauce. Keep warm or set aside to reheat before serving

Preheat an oven to 180°C/gas mark 4. Place an ovenproof frying pan over a high heat and a separate non-stick pan over a medium heat. Pour a few centimetres of oil into the non-stick pan

Sear the lamb all over in the ovenproof frying pan until well browned, then transfer to the oven for 6 minutes to finish cooking. Meanwhile, shallow-fry the potato cakes until golden on both flat sides and heated through. If needed, reheat the sauce

To serve, divide the sauce between 4 shallow bowls. Place the potato cakes on top, alongside the lamb. Garnish with coriander and serve with rice