1. To make the marinade,crush the garlic and oregano leaves in a mortar and pestle to form a rough paste. Rinse the preserved lemon and cut away and discard the inside flesh. Chop the rinsed skin,add to the mortar and crush everything together.
2. Sprinkle the lamb shoulder with 1 tbsp salt and season with black pepper,then rub the marinade all over both sides of the shoulder. Refrigerate on a baking tray,covered,for at least 8 hours or overnight.
3. The next day,remove the lamb from the refrigerator and allow it to come to room temperature. Preheat oven to 180C (160C fan-forced). Cut the potatoes in half and place in a deep roasting dish where all the ingredients will fit snugly in one layer. Set aside.
4. Heat the olive oil in a large frypan over medium-high heat and cook the onion until deeply caramelised,about 10-15 minutes. Pour the onion and oil mixture over the potatoes. Add tomato,garlic cloves and herbs to the roasting dish. Drizzle the lemon juice over everything.
5.Add the stock to the same frypan with the extra ½ tsp salt and bring to a boil. Place the lamb in the centre of the roasting dish,moving some of the potatoes aside so it sits on the bottom of the dish. Pour the stock over the potatoes – add just enough to come three-quarters up the sides of the potatoes.
6. Cover the dish with aluminium foil and bake for 1½ hours. Flip the shoulder over,re-cover it with foil and continue braising for another hour (you may need to add more water or stock to the pan if it looks like it's drying out). Pull the meat out of the oven and take a look at it. If it still feels tough,cook for another hour,covered. Once it is starting to become tender and the bone is loosening,remove the foil and return the lamb to the oven,presentation side up,and continue cooking for a further 30 minutes to brown everything and get the meat meltingly tender.
7. When the meat and potatoes are browned,remove the lamb from the tray to rest for at least 15 minutes. If you want to brown the potatoes further,pour off the braising juices into a small pot and continue roasting the potatoes while the lamb rests.
8. To serve,place the meat on top of the potatoes. Taste the juices,adjust seasoning if needed,and warm. Serve juices in a gravy dish on the side so each guest can add more to their plates if desired.
Serving suggestion:with myroasted carrot salad on the side andsalted caramel mousse for dessert.
Tips:
*If you can't find preserved lemon,use the fine zest of a fresh lemon.
These flavours are Mediterranean but use whatever herbs and spices you prefer.
Keep an eye on the lamb shoulder as it cooks. You want the meat to be fall-apart tender before removing the foil to brown at the end.