Cloud ear - it's a rather exotic sounding name for a type of fungus. This fungus has been featured in Chinese cooking since the sixth century. The Chinese name for name for cloud ear is mo-er, or "little ear" - as the photograph illustrates, it does vaguely resemble a human ear when fresh.
Like tofu, cloud ear - auricularia auricula to use its scientific name - has no flavor of its own, but soaks in the flavors that it is cooked with.
The delicate, crinkly fungus is also valued for its crunchy texture. You'll often find cloud ear added to hot and sour soup, and it is also featured in stir-fried dishes.
Storage and Usage
Cloud ears are sold mainly in dried form, in plastic bags. If stored in an airtight container, they should keep for up to a year. Before using, soak the fungus in warm water for at least fifteen minutes. It will puff up to several times its normal size. Then rinse the fungus and trim the stem where it was attached to the wood of the tree (cloud ears grow on trees such as the mango and kapok). Once the cloud ears have been cut up into an appropriate shape and size, add them to a dish near the end of stir-frying, so that they do not lose their crunchy texture.
Cloud ear is often confused with wood ear, a distance relative of the cloud ear fungus that also grows on trees. While cloud ear is smaller and more tender, the two types of fungi can generally be used interchangeably.
Feel free to use either (or both) in Hot and Sour Soup.