How to Rehydrate and Use Dried Mushrooms

Before use, soak dried mushrooms in warm water for 20–30 minutes, pressing them down, until they soften; cold water significantly lengthens this time, while boiling water can damage the mushrooms’ texture and make it rubbery. You can place a small plate on top to keep the mushrooms submerged. Never discard the soaking liquid: it carries much of the mushrooms’ concentrated umami aroma, and straining it into a dish noticeably enriches the flavor. With strongly flavored varieties such as porcini, this liquid has an almost stock-like depth of flavor.

How Long Should Dried Mushrooms Soak?
The standard is to soak them in warm water for 20–30 minutes; the time may vary depending on the variety and slice thickness, and thickly cut mushrooms may take a little longer. They are ready when they feel flexible and soft when gently squeezed with your fingers. If a mushroom is still hard and dry in the center, it has not soaked long enough; leave it in the water for a few more minutes. If you use it in a hurry, it will remain tough after cooking too. Large pieces left whole always take a little longer to soften than smaller pieces cut in half beforehand.

Why Should You Keep the Soaking Liquid?
During drying, the mushroom’s aroma compounds become concentrated, and much of them transfer into the water as the mushrooms soak; that is why the soaking liquid is almost like ready-made mushroom stock. Strained and added to soup, risotto, or sauce, it gives the dish a deep umami flavor. Even if you are not using it right away, you can store this liquid in the freezer; freeze it in small containers and thaw it as needed for other dishes. Stored this way, the liquid can be used within a few months with almost no loss of aroma.

How Should You Prepare Mushrooms After They Soften?
Remove the softened mushrooms from the water, squeeze them gently, then chop them or leave them whole as the recipe requires. In varieties with tough stems, the stem usually remains more fibrous; removing it and using only the caps gives a better texture. You can sauté the prepared mushrooms directly or add them to a cooked dish. Because their aroma is more concentrated than that of fresh mushrooms, a little less than the amount specified in the recipe is usually enough.

What Should You Do If There Is Sand or Sediment in the Soaking Liquid?
With some wild or forest mushroom varieties, fine sand or soil sediment can collect at the bottom of the soaking liquid; if you add the liquid directly to a dish, it can leave a gritty texture when you chew. Straining the liquid through a fine-mesh strainer before use solves this problem. If there is a lot of sediment, put a folded paper towel or a piece of fine cheesecloth in the strainer; this catches even the smallest particles and gives you a completely clear liquid.

How Long Can Dried Mushrooms Be Stored?
Unopened packages of dried mushrooms can retain their freshness for up to one year in a cool, dark cupboard. After opening, transfer them to an airtight jar and keep it in a dark place. Mushrooms exposed to moisture can start to mold, so keep them away from damp kitchen cupboards. Do not use dried mushrooms that have darkened in color or smell moldy; these signs indicate that the mushrooms have spoiled and are no longer safe to eat.