1.Combine beef, lemon grass, chopped onion, garlic and egg white in medium bowl by hand. Roll level tablespoons of the mixture into balls.
2.Heat stock, star anise and cinnamon in large saucepan and bring to a boil. Reduce heat and simmer uncovered for 5 minutes. Add meatballs and return to a boil. Reduce heat and simmer uncovered for another 5 minutes or until meatballs are cooked through. Discard star anise and cinnamon from pan.
3.Meanwhile, place noodles in large heatproof bowl, cover with boiling water, stand until just tender and drain.
4.Divide noodles, meatballs and stock among serving bowls and top with combined sprouts, coriander, chilli and sliced onion. Serve with lime wedges, if desired.
Pho, the well-known vietnamese noodle soup, is usually eaten for breakfast, but is great to eat at any time of the day.