A long braise in the oven yields fork-tender results for a tough cut of lamb. Cinnamon, oregano, garlic and lemon infuse the lamb shoulder with Mediterranean aromas, while a final scattering of pomegranate arils provides a burst of color and crunch.
Zest 1 lemon. Combine the zest, 5 garlic cloves, 3/4 teaspoon salt, oregano and cinnamon in a mortar and pestle or mini food processor and blend into a paste. Rub the mixture all over lamb and place in a 5 1/2-quart ovenproof pot with a tight-fitting lid (the lamb should fit with just a little space around the edges). Refrigerate for at least 2 hours or overnight.
Preheat oven to 300 degrees F.
Squeeze the juice of the zested lemon over the lamb. Cut the remaining lemon in half and tuck around the lamb along with the remaining 5 garlic cloves, potatoes and onion. Sprinke the vegetables with the remaining 1/2 teaspoon salt. Pour water around the lamb in the pot.
Cut a piece of parchment paper a bit larger than the pot. Wet the parchment and use it to cover the lamb and vegetables, crumpling and tucking it down around the edges. Braise the lamb until fork-tender, 4 to 5 hours.
Discard the parchment. Increase oven temperature to 425 degrees F. Baste the lamb with the pan juices and continue cooking until the top is browned, 10 to 15 minutes more.
Cover the pot and let stand for 15 minutes. Transfer the lamb to a serving platter along with the potatoes, onion and garlic. Sprinkle with pomegranate arils and parsley before serving.
Equipment: Parchment paper