Fresh shiitake mushrooms are available, but Thai cooks prefer to use them dried as they have a stronger flavour and more texture.
Both types are available in supermarkets and Asian stores. Dried shiitake must be reconstituted in water before being used. The stems are usually discarded and the caps sliced or chopped for adding to soups or stews.
The soaking water can be strained and used in a soup or stock as it takes on the flavour of the shiitake.
The dried mushrooms will keep well if stored in a sealed plastic tub or bag in a cool, dry place.
They are also called Chinese dried black mushrooms.
Their distinctive woody, smoky tastes are intensified by the drying process and they are rarely eaten fresh.