When you soak dried mushrooms in hot water to rehydrate them, never discard the water, which will be a wonderful mushroomy elixir. Strain it through a sieve lined with dampened paper towels or a coffee filter, and add it to your dish if there’s a liquid component (e.g., in soup or risotto). If you can’t use it right away, the soaking liquid is worth freezing for later use.
If your dried shiitakes (Chinese black mushrooms) have stems attached, cut them off after the mushrooms are rehydrated, but don’t toss them, either. They’re too tough and fibrous to eat, but they have lots of flavor and can be used, along with strained soaking liquid, to flavor a stock or broth.
CindyJ uses marsala, madeira or sherry to reconstitute dried porcini, then strains it and uses it in her recipe. Chicken stock is another makes another double-duty mushroom soaking medium.