Rinse lentils and pick over any discoloured lentils or foreign matter. Put lentils in the bottom of a large casserole dish.
Place carrot, celery and crushed garlic on top of lentils. Top with lamb shanks. Pour canned tomato over evenly. Add the bay leaves, thyme and dried parsley. Press gently into the liquid.
Cover tightly. If you do not have a tight fitting lid for your casserole use foil. Sometimes it is easier to use two pieces of foil to get a really tight fit. Cook on 150oC for 2 to 2 1/2 hours.
Remove lamb shanks. Skin the fat from the surface of the casserole. Mix contents well. Serve lentils on plates and top with lamb shanks and fresh parsley.