A Quick Porcini Primer

• To biologists and mycologists, porcini are known as Boletus edulis, or the king bolete. They grow in temperate forests around the world, from Europe and Asia to North America and New Zealand. The season for fresh porcini spans late summer and early fall, and they're harvested from the wild rather than cultivated. That means the fresh mushrooms are rare and costly, but dried porcini are readily available at most supermarkets. Look for packages with large intact pieces and without visible worm holes. The dried porcini should have a powerful smell when they're opened, indicating freshness and flavor. Rehydrate a 1/2-ounce package of dried porcini in no more than 1 cup of warm water to minimize flavor loss.

Add It to Your Main Dish

• Rehydrate your mushrooms in more or less water, depending on whether the water or the mushroom is more important to your dish. Many recipes call for a specific amount of soaking water, because the aroma-laden water is crucial to the finished dish. For example, if you're making a mushroom pilaf or risotto, you might incorporate the soaking water -- carefully strained to remove debris -- into the cooking liquid for the rice. Like the mushrooms themselves, the soaking liquid adds a potent, earthy flavor to the rice. The same holds true of mushroom sauces for pasta.

Make Soup or Sauce

• Not all recipes incorporate the soaking liquid, which frees inventive cooks to improvise with this flavorful ingredient. Well-strained porcini liquid can make a fine addition to mushroom soup or mushroom consomme, where it elevates the flavor of less-exalted species. It's good in rich, dark soups, such as duck or beef-barley, where it complements the meat and root vegetables. Simmered and concentrated to 1/4 or 1/3 of its original volume, it can also add a pronounced mushroom flavor to cream-based sauces, gravies or vegetarian grain dishes. If you have no immediate use for the porcini liquid, freeze it in ice cube trays, then transfer it to heavy-duty freezer bags for later use.

Upgrade White Mushrooms

• Porcini mushrooms' many fine qualities come at a cost. For many cooks, using only porcini in a mushroom-heavy dish just isn't in the budget. However, once the porcini are rehydrated, their liquid can add a potent flavor to ordinary white mushrooms. Saute sliced mushrooms until they release their own juices into the pan, then add the porcini liquid. As the liquids of the mushrooms mingle and evaporate, their combined flavors are concentrated and absorbed back into the button mushrooms, lending them a share of the porcinis' commanding presence in your finished dish.