Lamb Shanks with Creamy White Beans and Yellow Turnip Puree

FOR THE LAMB:
Preheat the oven to 300 degrees F. In a large, flameproof casserole or roasting pan with a lid, heat the oil over medium-high heat. Season the lamb shanks with salt and pepper. In batches, without crowding, cook the lamb shanks, turning occasionally, until nicely browned on all sides, about 8 minutes. Transfer to a plate and set aside.

Pour off all but 2 tablespoons of the fat. Reduce the heat to medium and add the onion, carrot, and garlic. Cook, stirring often, until the vegetables brown deeply, about 10 minutes. Add the wine and bring to a boil. Cook until reduced to about 1/4 cup, 10 to 15 minutes. Return the shanks to the casserole. Add the stock, water, thyme, lemon zest, and peppercorns and bring to a boil. Tightly cover the casserole.

Bake until the lamb shanks are very tender, about 1 3/4 hours. Turn the shanks occasionally and check that they are not cooking too fast--the braising liquid should be barely simmering. Lower the oven temperature, if necessary. Continue cooking for approximately 45 minutes longer until, when tested with a fork, the meat easily separates from the bone.

TO ASSEMBLE:
Transfer the lamb shanks to a large platter and cover with aluminum foil to keep warm. Spoon off the fat on the surface of the braising liquid, and place the casserole over high heat. Bring the cooking liquid to a boil and cook until richly flavored and reduced to about 1 1/2 cups, about 10 minutes. Strain the sauce and season with salt and pepper.

Place a lamb shank in the center of each of 6 warmed dinner plates. Holding the meaty end with one hand, bring up the shank bone into a vertical position with the other hand, pressing down so the meat releases from the bone at the meaty end to form a base for the shank to stand in. Place a mound of turnips at the ten o'clock position, and a spoonful of beans at the two o'clock position. Spoon the sauce over and around the lamb shank and garnish with a sprig of thyme. Or, leave the lamb shanks on the platter and garnish with the thyme. Place the turnip puree and beans in individual serving bowls, and pour the sauce into a warmed sauceboat.

VARIATIONS:
Creamy polenta may be substituted for the turnips to provide a very different counterpoint to the lamb and beans. Also, peas and pearl onions make an effective springtime alternative to the white beans.