Of course the lamb is supposed to be the star here, but the vegetables are a revelation. They soak up the lamb juices as they cook, becoming really imbued with the flavour both of the lamb and of the sherry. You have all you need in one dish here, but if you want something green, make Olive oil-roast sweet & sour leaves with raisins and pine nuts (see page 117).
8 garlic cloves, plus 1 head of garlic, cloves separated
sea salt flakes and freshly ground black pepper
large pinch of saffron threads (optional)
leaves from 8 thyme sprigs, plus 4 whole thyme sprigs
8 tablespoons extra virgin olive oil
2kg (4lb 8oz) leg of lamb
1 large onion, cut into wedges
300g (10½oz) slim bunched carrots, or, if you can only find fatter carrots, halve or quarter them lengthways
500g (1lb 2oz) waxy potatoes, scrubbed and sliced (no need to peel)
400ml (14fl oz) amontillado sherry, plus more if needed
Preheat the oven to 220°C fan (450°F), Gas Mark 8.
Crush the 8 cloves of garlic in a mortar and pestle with some sea salt flakes (the salt flakes act as an abrasive). Grind in the saffron, if using; it will add its flavour, and of course its gorgeous colour, but the dish is just as delicious without. Add the thyme leaves, pepper and olive oil, to give a loose paste.
Make incisions all over the lamb with a knife and slightly loosen the meat around the bone end, too. Push the garlic and herb paste down into these incisions, into the space around the bone and all over the joint. Put into a large roasting tin or a cast iron casserole; you will need to add all the vegetables later, too, so there has to be room for them as well. Season all over.
Roast for 20 minutes, then remove the tin or casserole from the oven. Reduce the oven temperature to 160°C fan (340°F), Gas Mark 3½. Put the onion, carrots, the rest of the garlic cloves, potatoes and thyme sprigs under and around the lamb. Bring the sherry to just under the boil, then pour it over. Cover tightly with a double layer of foil, or the lid, and return to the oven.
Cook for 2½ hours, turning the lamb over about 3 times and checking on the sherry, too: most of it will be absorbed during cooking, but don’t let it get dry. If there are a lot of juices, remove the foil or uncover the pot 45 minutes before the end of cooking time, so they can reduce. The lamb should be cooked to softness – if it isn’t, cook it for a little longer – and the vegetables completely tender. Serve the lamb with the vegetables and the sherry juices.