Trim fat from meat; cut meat into 3/4-inch cubes, and sprinkle with pepper. Heat oil in a Dutch oven over medium-high heat. Add meat, and cook 3 minutes or until browned, stirring frequently. Add soy sauce and next 4 ingredients (soy sauce through cinnamon); stir in star anise, if desired, and bring to a boil. Cover meat mixture, reduce heat, and simmer 1 hour.
Add carrot and leek; cook, uncovered, an additional 30 minutes or until vegetables are tender. Discard gingerroot, green onions, cinnamon, and star anise. Serve over couscous.