Rinse and pat dry the fish; cut it into 5cm chunks. Mix all the marinade ingredients in a bowl, add the fish and chill for at least 30 minutes.
Core and chop the pepper into strips or dice; slice the mushrooms, slice the beans lengthwise. Trim the spring onions and chop them into 1-2cm pieces.
Soak the noodles: bring a pan of water to the boil, drop the noodles and soak them for 5 minutes.
In the meantime heat the oil in a wok over medium heat. Add the fish with the marinade and spread it over the bottom of the wok in a single layer. Cook for a minute, then turn the fish pieces over using chopsticks or tongs.
When the fish has barely turned opaque, remove it back to the bowl and keep aside.
Add all the vegetables except spring onions to the wok and turn the heat up a little. Stir around to dislodge the marinade that might have stuck to the bottom, add cup of water and cover with a lid or a tray. Cook for 3 or 4 minutes, stirring now and again.
At this point drain the noodles, stir a little chili oil into them and keep warm.
When the vegetables look cooked, return the fish with its sauce into the wok, add the spring onions and stir gently. Cover the wok with a lid and let the fish steam for a minute or two.
Divide the noodles between serving bowls or plates and pile the fish stir fry on top. Serve with lime quarters.
