To make the filling for the won tons, put the mushrooms in a small bowl, cover with boiling water and soak for 15 minutes, or until rehydrated. Remove the stems and discard. Finely dice the caps and combine with the mince, cornflour, oyster and soy sauces and sesame oil.
Place about 2 teaspoons of filling on a won ton wrapper and gently gather the edges together to enclose the filling. Repeat until you have 32 won tons.
Combine the soup ingredients and 2 cups of water in a saucepan and bring to the boil, then cover and reduce to a gentle simmer. Meanwhile, bring a large saucepan of water to the boil. Set out four large Chinese soup bowls.
Cook the noodles in the pan of boiling water for 2 minutes, then remove from the water and strain. Lift into the soup bowls. Cook the buk choy in the same pan for 1 minute, or until bright green but still crunchy. Use a slotted spoon to lift into a strainer, then add to the bowls.
Cook the won tons for 3–4 minutes in the same water; they will float to the surface when cooked. Remove with a slotted spoon and lift into the bowls. Ladle in the soup and sprinkle with spring onions. Serve with a small bowl of hot chilli sauce and another of soy sauce and sesame oil.
• You can use any type of noodle you like, such as Hokkien noodles, dried rice noodles or long-life noodles. If you are using dried noodles you'll only need about 250 g. * • If you can't find won ton wrappers you can use gow gee wrappers, or roll the filling into meatballs and dispense with the wrapping. * • The won tons can be made a few hours in advance and laid in a single layer on a tray. Cover tightly with plastic wrap and keep refrigerated until ready to use.