Definition:
These are not the black beans you'll find in Mexican cooking. Fermented black beans (also called salted or dried black beans) are made from soybeans that have been dried and fermented with salt; other spices such as chilies and/or wine and possibly ginger may be added. Because of their strong flavor, fermented black beans are frequently paired with other strong seasonings, such as garlic and chilies. They make a frequent appearance in Cantonese cooking; you’ll find them in dishes such as Shrimp With Lobster Sauce. Fermented black beans are normally rinsed before being used in cooking; otherwise, they will impart too much of a salty flavor to the dish. Often you’ll find recipes calling for the beans to be mashed with garlic.
Fermented black beans are sold in plastic bags in Asian markets. At home, remove the beans from the package and store in a sealed container in a cool, dark place. The beans will last for several months. You can also find fermented black beans sold in jars - these can be used instead if necessary but they don't have as much flavor.
If you don’t live near an Asian market, premade black bean sauce is often available in the international or ethnic section of many supermarkets. You can also purchase both fermented black beans and premade black bean sauce at several online stores specializing in Asian ingredients.
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