Step 1 Preheat oven to 200ºC. Lightly coat lamb shanks with flour. Heat the oil in a heavy- based flameproof casserole dish over medium heat. Add 2 shanks and cook, turning occasionally, for 8 minutes, or until browned on all sides. Transfer to a plate. Repeat with remaining shanks.
Step 2 Add onion to the casserole and cook, stirring often, for 4 minutes, or until soft. Add red and green capsicum and stir until well combined. Cook for 3 minutes, or until capsicum is tender. Add the chicken stock and lentils, and bring to the boil. Season with pepper. Return shanks to the casserole, cover and place in the oven for 1 hour, or until meat is very tender.
Step 3 Spoon lentil mixture among serving plates. Top with a lamb shank and sprinkle with parsley, if using, to serve.