This is a delicious and colourful stir fry. If you can't find king oyster mushrooms (also known as king trumpet mushrooms or French horn mushrooms) you can substitute in any other mushrooms you prefer.
1/2 tablespoon sugar
1/2 tablespoon light soy sauce or 1 tablespoon dark soy sauce
1 tablespoon cornflour, mixed with 1 tablespoon water