2.5-cm (1-inch) piece of fresh root ginger, peeled and grated
300 g (10 oz) chicken breast fillets, cut into strips
1 litre (1 3/4 pints) hot chicken stock
4 pak choi, sliced
175 g (6 oz) dried egg noodles
2 tablespoons sesame seeds
Heat the oil in a wok or large saucepan, add the ginger and stir-fry for 1 minute, then stir in the chicken and 125 ml (4 fl oz) of the stock. Bring to the boil, then cook over a high heat for 5 minutes or until the chicken is cooked through.
Add the remaining stock and bring to a simmer. Stir in the pak choi and noodles and simmer for 5 minutes until the noodles are cooked.
Meanwhile, heat a nonstick frying pan over a medium-low heat and dry-fry the sesame seeds for 2 minutes, stirring frequently, until golden brown and toasted.
Ladle the soup into bowls and serve sprinkled with the toasted sesame seeds.