Heat the oven to 150°C. Cut any large blobs of fat off the lamb. Finely grate six of the garlic cloves, place in a bowl and stir in the salt, lemon zest, 1 Tbsp (15 ml) of the oregano and the olive oil.
Using a sharp knife, pierce the thick parts of the lamb (top and bottom) in 8–10 places,at a diagonal, to a depth of 3 cm. Push a little garlic paste deep into each cut and rub any remaining paste over the top of the joints. Put the onion slices and remaining garlic cloves into a large roasting pan and place the lamb on top.
Sprinkle with the remaining oregano and plenty of black pepper, pour in the wine and lemon juice and cover tightly with two layers of heavy foil. Place in the oven.
After 3½ hours, remove the foil, turn the heat down to 140 °C and switch off the oven fan. Season the lamb with salt, to taste. Roast, basting now and then with the pan juices, for a further 1½ hours, or until the lamb is brown and sticky and falling off the bone. Top up with more wine and lemon juice if necessary: the liquid in the pan should be about 1 cm deep.
For the potatoes, cut out eight circles of baking paper, each the size of a dinner plate. Prick the potatoes and divide them between the paper circles.
Season with salt and pepper and add a knob of butter, a sprig of thyme, a sprinkling of lemon zest, and any other flavourings you fancy. Fold each circle in half to make a semicircle and tightly seal the edges by making small, overlapping pleats all the way round.
Brush the tops of the parcels with melted butter and place on a baking sheet. An hour before you’re ready to serve the lamb, place the parcels in the oven and bake for the remaining time or until quite tender (see Notes).
Lay a bed of flat-leaf parsley on a large platter and place the lamb on top. Cover with foil and allow to rest for 10 minutes. Pour the juices from the pan into a small jug and skim off the fat. Serve hot, with the potato parcels, and pass the pan juices round in a jug.
permission of Scrumptious South Africa and published by Random House Struik.