Soak the rice vermicelli in boiling water for 4 minutes. Drain, refresh under cold water, drain again and set aside.
Mix soy, fish sauce and oyster sauce in a bowl. Heat the sunflower oil in a large wok, add spring onions, chopped garlic cloves and the deseeded and chopped chilli.
Stir fry for 20 seconds before adding the thinly sliced shiitake or chestnut mushrooms and broccoli florets. Stir fry for 1 minute, then add the pak choi and the sauce mixture. Stir and cook for about 2 minutes over a high heat, adding a splash of water if the sauce becomes too thick.
Tip in the noodles, remove from the heat and toss to mix well. Serve in warmed bowls and tuck in with your chopsticks.