This is a recipe that I first made as an alternative to roasting a leg of lamb. I wanted to save time and make my own gravy, so I turned it into a pot roast by adding vegetables and wine. I think shoulder of lamb is one of the best cuts by far – it's tastier than leg and much more economical.
Preheat your oven to 200ºC/400ºF/gas 6. Rub the lamb with oil, sea salt and freshly ground black pepper and put it into a roasting tray. Using a sharp knife, make small incisions all over the lamb and poke rosemary leaves and some quartered cloves of garlic into each one. This will give great flavour to the meat. Add the rest of the garlic cloves, the onions, carrots, celery, leeks and fresh tomatoes to the tray, then tuck the remaining herbs under the meat.
Pour the tinned tomatoes over the top, followed by the wine. Cover the tray tightly with a double layer of foil and put it into the oven. Turn down the oven temperature to 170ºC/325ºF/gas 3 and cook for 3½ to 4 hours, or until the lamb is soft, melting and sticky and you can pull it apart with a fork. Gently break up the meat, pull out the bones, and extract any herb stalks. Squeeze the garlic out of the skins and mush it in. Shred the lamb, check the seasoning and serve with some crispy roast potatoes.