Soybeans; Fermented Soybeans

Soybeans, Glycine max, have been cultivated for about five thousand years in China. Because the soybean is a legume, it fixes nitrogen in the soil, so it’s often grown in rotation with rice (soybeans in dry season, rice in rainy season). In Burma soybeans (peipok si) are used to make tofu and are also eaten as fresh beans. Soybeans grow in a green pod, and although fresh soybeans can be difficult to find in North America, frozen soybeans, either in their pods or shelled, are sold in Asian groceries and in larger supermarkets too. They are often referred to by their Japanese name, edamame. Raw soybeans are not digestible because they contain protease inhibitors, but these disappear with cooking. Fermented soybeans, sold in glass jars in Chinese and Southeast Asian groceries, are soft, slightly salty soybeans that give a meaty umami depth of flavor; they may be sold whole or as mashed beans. The Burmese name is pei ngapi (bean ngapi), which explains their role as equivalent to that of ngapi, to give umami in a dish. Look for jars labeled “preserved soybeans,” “soybean paste,” or “fermented soybeans,” and check the list of ingredients: you want them to be limited to salt, water, and soybeans, with no sugar or other flavorings. The beans are a pale brown and very soft. They can be mashed in a mortar with a pestle, but also by placing them in a bowl and pressing them with the back of a spoon, a matter of a couple of minutes. Brown miso paste can be substituted, but since miso has a stronger flavor, use half or less than half the amount called for. See also tua nao.