Mix the seasoned flour and paprika in a plastic bag, add the lamb shanks and toss to coat. Reserve any remaining flour.
Heat the oil in a flameproof casserole or frying pan and brown the lamb shanks, a few at a time. Set aside. Stir in the onions and garlic and cook 2 minutes. Add the remaining flour and cook a further minute.
Stir in the beef stock and orange juice and, once a sauce is formed, add the prunes, barley, orange rind and thyme. Return the lamb shanks to the casserole or transfer to one. Cover and bake at 160°C for 2-2½ hours or until the meat is tender. Season with salt and pepper if wished before serving.