Preheat the oven to 180°C (350°F).
In a bowl whisk together 4 tbsp Extra-virgin olive oil, the juice and zest of 1-2 Lemons, 4 minced cloves Garlic, 1 tbsp Oregano, 1 tbsp finely chopped Rosemary, 1–1½ tsp Sea salt and ½ tsp Black pepper to make a bright, aromatic marinade.
Rub the Lamb shoulder all over with the marinade, making sure to get it into any folds or scores; cover and refrigerate for at least 30 minutes or up to overnight so the flavors penetrate.
Peel (if you like) and cut the Potatoes into large wedges. Toss them with a little extra Extra-virgin olive oil, a pinch of Sea salt, and a little Black pepper — you can also sprinkle a bit more Oregano if desired.
Set the marinated Lamb shoulder in a roasting pan and arrange the seasoned Potatoes around it. Pour about 1 cup of Water into the bottom of the pan to help keep the lamb moist and create pan juices; tuck any used lemon halves into the pan for extra flavor.
Cover the pan with foil or a lid and roast at 180°C for 1½–2 hours, then remove the cover and roast uncovered for another 30–45 minutes, basting occasionally, until the lamb is tender and the potatoes are golden and crisp at the edges.
Remove from the oven and let the roast rest for 10–15 minutes so the juices redistribute. Taste and adjust seasoning with more Sea salt and Black pepper if needed, then carve the lamb and serve the potatoes spooned with the pan juices.
