Combine ginger, garlic, star anise, soy and fish sauce with 2 cups water in a large saucepan. Bring to the boil over high heat. Reduce heat to low. Add chicken and simmer for 10 minutes until just cooked. Remove ginger and star anise and discard. Transfer chicken to a plate, then shred when cooled. Add stock to the pan and return to simmer.
Meanwhile, place noodles in a heatproof bowl. Cover with boiling water. Stand for 5 minutes. Drain.
Divide noodles between serving bowls. Top with chicken. Ladle stock mixture into bowls. Top with bean shoots, herbs, shallot, onion, and chilli.
This aromatic soup can also be made with prawns. Cook 400g peeled green prawns for 4 minutes or until they change colour.