Dried Mushrooms: Dehydrated, Concentrated Earthiness
It's hard to believe that your dinner can benefit from something that looks so dry. But when you open the bag, that first smell gives you a hint of how much flavor is trapped in those shriveled mushrooms.
Dried mushrooms, as with everything else, run the quality gamut. Unfortunately, price is often (although not always) an accurate indication of that quality. Cheap dried mushrooms are almost always bland, and flavorful dried mushrooms are almost always expensive. Shop around, buying in small quantities, until you find a version you like.
You'll see all kinds of mushrooms in dried form - shiitakes, morels, chanterelles, and even portobellos and creminis. My favorite are porcini, since their robust flavor stands up well to the drying process - just a few dried porcinis can lend mushroom flavor to a whole dish.
You don't have to keep dried mushrooms in the refrigerator, but I do anyway, because I found that bugs love them almost as much as I do.
Dried mushrooms have to be hydrated, soaked in hot water for at least 20 minutes, but longer is better.
The mushroom hydrating process yields two edible components and two inedible components. The useable parts are the mushrooms themselves and their liquid, and I'm not sure which is more valuable. Finely chop the mushrooms and add them to whatever mushroom dish you're making, and use the liquid for soup, stew, or sauce. The best uses for dried mushrooms are dishes that use both parts.
If you want to truly make a risotto that will spread your culinary fame across your universe, try soaking a bunch of dried cremini or porcini overnight. Then take out the mushrooms and set aside. Place the liquid on the stove, and toss in a good healthy gram (or even two if you can afford it) of true Spanish saffron threads. Bring to a boil and sieve out the threads. Now sauté some fine Arborio rice in butter until it's barely golden and start adding a cupful at a time of the boiling liquid while you stir your arm off. Keep going until the rice is just barely al dente. Now throw in the reserved mushrooms, a whole bunch of frozen (yes frozen) peas, and continue stirring and adding liquid until the rice is done and the peas are just barely warm through. Remove from the heat, toss in an ungodly amount of freshly grated Parmigiano Reggiano, stir to melt and eat! You are going to enjoy a risotto that could easily be served at a Michelin starred restaurant! Whoooohoooooooooooooo!
The two unusable byproducts of the reconstituting process are grit and the tough parts of the mushrooms. The first is sediment, which inevitably falls out of the mushrooms and settles at the bottom of the bowl. Make sure you leave it behind when you drain off the liquid. The second is the mushroom parts that don't rehydrate properly - stems and sometimes parts of caps. Feel the rehydrated mushrooms for any stiff parts, and cut them off.
Use dried mushrooms almost anywhere you'd use the fresh kind - or use dried and fresh together.