Marinated Lamb

Combine the brine ingredients in a large pot and bring to the boil. Remove from the heat and allow to cool completely. Add the lamb to the brine and place in the fridge, covered, for 24 hours.
Preheat the oven to 130˚C.
Remove the lamb from the brine and pat dry with paper towel. Heat the oil in an ovenproof casserole dish large enough to fit the lamb, over high heat. Brown lamb, turning, for 3–4 minutes until evenly coloured. Cover the dish with a lid or foil and transfer to the oven. Cook for 3½–4 hours until the lamb is almost falling from the bone. Remove the lamb from the casserole pan and rest, covered, for 20 minutes.
Meanwhile, transfer the pan juices to a saucepan and bring to the boil over high heat. Cook for 5 minutes until reduced by one-third. Whisk in the butter, a few cubes at a time, until incorporated. Add lemon juice and season to taste with pepper.
Carve the lamb into slices and serve with pan juices.