Soak the mushrooms in warm water with the sugar for
30 minutes then drain, reserving 120ml/1/2 cup of
the liquid. Discard the stalks and halve the caps.
Heat 30ml/2 tbsp
of oil and stir-fry the mushrooms for 2 minutes.
Add the soy
sauce, wine or sherry and salt. Stir in the
remaining oil, mushroom liquid and sugar, cover and
simmer for 30 minutes, stirring occasionally.
Blend the corn
flour to a paste with a little water then stir it
into the pan and simmer, stirring, until the sauce
thickens. Pour over rice to serve.