To make the paste put the first 11 ingredients into a food processor and whizz to a paste. Set aside.
Heat the oil in a large shallow casserole dish then brown the shanks all over really well. Remove from the pan. Tip the curry paste into the pan and fry for a minute, or until fragrant. Return the lamb to the pan with the coconut milk, stock and the potatoes, give everything a good stir. Bring to a simmer then cover and cook for 2-2 1/2 hours, or until the lamb is fork tender and the sauce is reduced. If you like a thicker sauce, remove the lamb and keep warm then increase the heat and bubble the sauce until you reach the consistency you like.
Serve the curry with sauce, coriander leaves, lime wedges, a scattering of cashew nuts and some steamed rice.
Freezing and defrosting guidelines
Cook as instructed and allow to cool completely. Then transfer to an airtight, freezer-safe container, seal and freeze for up to 1-3 months. To serve, defrost thoroughly in the fridge overnight before reheating. To reheat and serve, place on medium heat, stirring occasionally until the dish is heated through.
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