Cook the rice noodles in salted water according to the packet instructions.
Blanch the beans in boiling salted water for 5-6 minutes.
Refresh in cold water and drain.
Lightly oil 2 bamboo steamers.
Put the spring onions, pak choi, beans and snow peas into the bamboo steamers.
Bring water to a boil in a wok, place the covered steaming baskets over the wok and steam for 5-6 minutes.
Put the coconut milk into a pan with the tom yum paste and bring to a boil. Boil for 4 minutes.
Add the coconut, lime juice and fish sauce to taste.
Put the vegetables on plates with the noodles and coconut sauce and serve garnished with coriander and chilli.