Heat the sesame oil in a heavy-based pot over a medium heat.
Add the onion and ginger and cook for about 5 minutes until slightly golden and crunchy.
Add the mushrooms, cardamom, coriander, star anise and stock.
Heat until barely simmering and add the chicken breasts.
Cover and cook for 10 minutes until the chicken is cooked through, then remove the chicken and place on a board to cool.