How to Make It
Preheat the oven to 325°. Heat the olive oil in a large enameled cast-iron casserole. Season the lamb shanks with salt and pepper. Add 3 shanks to the casserole and cook over moderate heat until browned all over, about 8 minutes; transfer to a plate. Add the remaining 3 shanks and the rosemary to the casserole and cook until browned. Add the minced garlic and cook for 1 minute. Remove from the heat and return the first 3 shanks to the casserole.
Using a sharp knife, remove the pulp from the lemon; discard the pulp. Cut the lemon rind into 8 pieces and add to the lamb along with the verjus, stock, garlic cloves, bay leaves, cracked peppercorns and 1 teaspoon of salt; bring to a boil. Cover tightly and braise in the oven for 3 hours, or until the meat is tender; turn the shanks occasionally.
Transfer the lamb to a platter; let cool slightly. Pull the meat off the bones and trim any fat. Discard the rosemary stems and bay leaves and skim as much fat as possible from the sauce in the casserole. Return the meat to the sauce and cook over moderate heat until warm. Spoon the lamb into bowls and serve.