Doenjang is a traditional Korean fermented soya bean paste. Its name literally means "thick paste".
To produce doenjang, dried soya beans are boiled and stone-ground into coarse bits. This paste is then formed into blocks, which are called meju. The blocks are then exposed to sunlight or warmth, when dried rice plants are attached to the surface of the soya bean blocks. Dried rice plants are readily available in Korea and are a rich source of bacteria (Bacillus subtillis). The fermentation process begins at this stage. The Bacillus subtillis bacteria reproduce, consuming soya bean protein and water in the meju. The unique smell of the meju is mainly the ammonia which is produced by the bacteria. One to three months later, depending on the block size, the meju are put into large opaque pottery jars with brine and left to further ferment, during which time various beneficial bacteria transform the mixture into a further vitamin-enriched substance (similar to the way milk ferments to become yogurt). Liquids and solids are separated after the fermentation process, and the liquid becomes Korean soya sauce (Joseon ganjang). The solid, which is doenjang, is very salty and quite thick, often containing (unlike most miso) some whole, uncrushed soya beans.
While traditional homemade doenjang is made with soya beans and brine only, many factory-made variants of doenjang contain a fair amount of wheat flour just like most factory-made soya sauce does. Some current makers also add fermented, dried, and ground anchovies to accentuate the doenjang's savoury flavour.
Doenjang can be eaten as a condiment in raw paste-form with vegetables, similar to the way some people dip celery into cheese. However, it is more commonly mixed with garlic, sesame oil, and sometimes gochujang to produce ssamjang which is then traditionally eaten with or without rice wrapped in leaf vegetables such as Chinese cabbage. This dish is called ssambap. It can also be used as a component of soup broth, for example in a popular stew (jjigae) called doenjang jjigae which usually includes tofu, various vegetables such as chilli peppers, courgettes and spring onions, and (optionally) mushrooms, red meat, or scallops.