In a bowl whisk together 3 tbsp olive oil, 1 tbsp lemon zest, 2 tbsp lemon juice, 2 tbsp chopped oregano, 4 minced garlic cloves, 1 tsp Dijon mustard, 1 tsp honey, 1.5 tsp kosher salt and 1 tsp black pepper until emulsified.

Marinate the lamb

Pat the lamb shoulder dry with paper towels. Rub the marinade all over the lamb, massaging it into any crevices. Place the lamb in a shallow dish or resealable bag, cover and refrigerate for at least 2 hours and preferably overnight (up to 24 hours) to allow flavors to penetrate.

Lemon & Oregano Potatoes

Prep the potatoes

If using larger waxy potatoes, cut into even 2–3 cm pieces; halve baby potatoes. Place potatoes in a large bowl.

Season potatoes

Toss potatoes with 2 tbsp olive oil, 2 tbsp lemon juice, 1 tsp lemon zest, 2 tbsp chopped oregano, 2 minced garlic cloves, 1 tsp kosher salt and 1/2 tsp black pepper until evenly coated. Set aside while the oven preheats so flavors marry.

To Roast & Finish

Preheat and sear

Preheat the oven to 170°C (340°F). Heat a large ovenproof skillet or Dutch oven over medium-high heat until shimmering. Add a thin film of oil or use some of the reserved marinade juices if available. Sear the lamb shoulder fat-side down for 4–5 minutes until well browned, then turn and brown the other sides for 3–4 minutes in total.

Add liquids and roast

Remove lamb briefly to a plate. Pour 250 ml stock and 60 ml white wine (if using) into the skillet, scraping up browned bits. Nestle the lamb back into the pan. Arrange the seasoned potatoes around the lamb in a single layer as much as possible. Cover the skillet or Dutch oven with a lid or tightly with foil.

Slow roast

Transfer to the preheated oven and roast for 2 to 2 1/4 hours, until the lamb is very tender and an instant-read thermometer inserted into the thickest part reads 90°C (195°F) or the meat pulls easily with a fork. Check once at the 1-hour mark: baste the lamb with pan juices and stir potatoes so they cook evenly. If potatoes look dry, spoon some pan liquid over them.

Crisp potatoes and finish

Remove the lid or foil and increase oven temperature to 220°C (425°F). Dot the potatoes and lamb with 2 tbsp cold butter (scattered cubes). Roast uncovered for an additional 15–20 minutes until potatoes are golden and edges crisp and lamb has a nicely caramelized surface. Baste once with pan juices during this time.

Rest and serve

Transfer the lamb shoulder to a cutting board and rest for 10–15 minutes tented loosely with foil. Stir chopped oregano into the potatoes and spoon any pan juices over them. Carve the lamb into slices or pull into large shreds and serve with the lemon & oregano potatoes, garnished with oregano sprigs and lemon wedges.