Pour the stock into a pan and add the chicken breast, ginger and garlic. Bring to the boil, then reduce the heat, partly cover and simmer for 20 mins, until the chicken is tender.
Put the chicken on a board and shred into bite-size pieces using a couple of forks. Return the chicken to the stock with the noodles, sweetcorn, mushrooms, spring onion and soy sauce. Simmer for 3-4 mins until the noodles are tender.
Ladle into two bowls and scatter over the remaining spring onion, mint or basil leaves and chilli, if using. Serve with extra soy sauce.
