Heat 2 tablespoons oil in a large Dutch oven over high heat. Add lamb shoulder, and cook, turning occasionally, until lamb is browned all over, 8 to 10 minutes.
Remove lamb; set aside. Pour out any excess oil, and discard. Add 1 tablespoon oil and heat over medium-high heat. Stir in garlic and onion. Cook for 1 minute then add spices. Cook for an additional 1 minute.
Return lamb to Dutch oven. Add wine and bring to a simmer. Let the wine reduce by half. Then add the lemon and enough water to cover 2/3rd of the shoulder and bring to a boil, cover, and transfer to the oven. Cook until fork-tender, 3 to 4 hours.
Remove from oven. Transfer lamb to a platter, and keep warm.
To make the sauce:
Place the Dutch oven over low heat, add butter and cook the liquid until it has reduced and thickened, about 3 minutes.
To serve:
Serve the lamb on top of roasted sweet potatoes. Drizzle the sauce all over and then top with pickled red cabbage, a drizzle of labne, and a sprinkle of sesame seeds.
