Using a vegetable peeler, remove the orange part of the peel from 1 of the oranges . Cut the peel into thin strips (should have about 1/4 cup); set aside. Squeeze the juice from both oranges to make about 2/3 cup. In a small bowl stir together orange juice, broth, cardamom, cumin, salt, turmeric, and pepper. Set aside.
Place carrots, onions, and garlic in the bottom of a 5- to 6-quart crockery cooker. Top with lamb shanks, strips of orange peel, and cinnamon sticks. Pour orange juice mixture over all. Cover and cook on low-heat setting for 8 to 9 hours or until lamb pulls easily from the bone.
When ready to serve, transfer the lamb shanks and vegetables to a serving dish using a slotted spoon. Skim the fat from the cooking liquid. Remove and discard the cinnamon sticks. Measure 1 1/2 cups juices; transfer to a small saucepan.
Combine water and cornstarch; add to saucepan. Cook and stir over medium heat until thickened and bubbly. Cook and stir 2 minutes more. Spoon sauce over lamb and vegetables. Sprinkle with olives and cilantro. Makes 4 to 6 servings.