Persian-style lamb and rhubarb stew

Method

1. Heat the oil and 30g butter in a large casserole over a medium heat. Add the onions and cook for 15 minutes. Add the garlic and cook for 1 minute. Set aside in a bowl.
2. Increase the heat, add half the lamb to the pan and brown all over. Set aside. Add the remaining lamb and brown as before. Return the onions and lamb to the pan, add the coriander and cook for 1 minute. Add the stock, cover and simmer gently for 1 hour. Season to taste.
3. Heat another 30g butter in a pan over a medium-low heat. Add the herbs and cook, stirring, for 8 minutes. Stir into the stew and simmer, half-covered, for 30 minutes, until the lamb is really tender.
4. Cool, spoon into a freezerproof container, cover and label. Freeze for up to 3 months. Thaw in the fridge for 24 hours. Reheat until piping hot.
5. Meanwhile, cut the rhubarb into 2.5cm lengths. Melt the remaining 30g butter in a large frying pan over a medium-high heat. Add the rhubarb, and cook, stirring, for 3-4 minutes, until just tender.
6. Stir the rhubarb into the stew and divide between plates. Scatter with mint and serve with couscous or rice.