In a saucepan, combine stock, water, ginger, cinnamon, star anise, cardamom, coriander seeds and fish sauce. Bring to a boil, reduce heat and simmer 10-15 minutes. Strain, discard the solids and return to the heat.
Meanwhile, place rice noodles in a bowl and pour boiling water over them. Let stand 5 minutes or until soft. Drain.
Add the chicken to the simmering stock. Divide the noodles between four bowls and ladle over the stock. Each guests chooses from the herbs to add to their bowl. Serve immediately.