Serves 4
Mint Sauce
For the mint sauce, put the mint into a small heatproof bowl and pour on the boiling water. Add the sugar and vinegar, stirring to dissolve the sugar, then season with salt and pepper to taste. Cover and leave to stand for 30min.
Lamb
Remove the lamb from the fridge 2 hours before cooking and season well with salt. Preheat the oven to 180C. Place the lamb into a large roasting tin. With the tip of a knife, make 2cm deep slits all over the lamb, spacing them at about 2cm intervals, then insert a slice of garlic into each one. Rub the lamb with olive oil, salt and pepper, then sprinkle over the thyme. Put the lamb into the oven for 1 hour. After 20min, turn it over and reduce the oven temperature to 160C; keep turning the lamb every 20min. After 1 hour, check the core temperature; you want the final reading, after resting, to be 60C, so aim for 55C to factor in the effect of the residual heat. Once that temperature has been reached, take out the lamb. Turn the oven down as low as it will go, or leave the door ajar, so the temperature drops to around 60C. Return the lamb to the oven to rest for 30min.
Carving
To carve the lamb, hold the shank with a tea towel. Take a sharp knife and cut down the bone, removing a large cut of meat. Turn the lamb and cut down each side of the bone, removing the remainder of the meat. You should now have two large pieces of meat. Slice each piece across the grain, creating semi-circular slices. Carving the meat like this gives the most tender result.
To Serve
Place the lamb on plates and drizzle with the juices from the roasting tin. Give it a sprinkle of salt and a good grind of pepper and serve with the mint sauce on the side.
Optional
Serve with new potatoes and braised peas.
Variations
Lamb and garlic are a match made in heaven, especially when lifted with the resinous flavour of rosemary; just insert a few rosemary leaves into each slit along with the garlic.
