|Onion||1 Medium, thinly sliced|
|Dry white wine||2 Tablespoon|
|Soy sauce||2 Tablespoon|
Rinse mushrooms briefly in cold water.
If stem ends are gritty, slice them off.
Cut mushrooms lengthwise through caps and stems into thick slices.
Melt butter in a wide frying pan over medium heat.
Add onion and cook until soft (about 5 minutes).
Add mushrooms, sugar, wine, soy, salt, and pepper.
Stir to blend.
Cook, stirring, over high heat until liquid is nearly gone (about 5 minutes).