How to Make It
Preheat the oven to 325°. In a large enameled cast-iron casserole, heat the olive oil until shimmering. Rub each lamb shank with teaspoon of the cinnamon and season with salt and pepper. Add the lamb shanks to the casserole and cook over moderately high heat until browned on all sides, about 12 minutes. Transfer to a platter.
Add the onion, celery and garlic to the casserole and cook over moderate heat, stirring occasionally, until the vegetables are softened and well browned, about 15 minutes. Stir in the date molasses and 2 cups of water and bring to a boil. Add the lamb and any accumulated juices and cover. Braise in the oven for 3 hours, turning once, until the meat is very tender.
Scatter the rhubarb and peas over the lamb in the casserole. Cover and braise for 15 minutes longer, until the rhubarb is tender. Transfer the lamb shanks to plates or a platter. Stir the mint into the vegetables and season with salt and pepper. Spoon the sauce and vegetables over the lamb and serve with steamed rice.
The recipe can be prepared through Step 2 and refrigerated overnight. Bring to room temperature before proceeding.
Date molasses is a complex, sweet and intensely flavored syrup made from dates. It is available at Middle Eastern markets and kalustyans.com.