Cu Da village in Hanoi’s, Vietnam been making soy sauce since its founding more than 400 years ago. In the past, every local household stored several jars of soy sauce to use all year round. Today, soy sauce is made not only for villagers's own use, but to sell outside the village. The soy sauce is made from glutinous rice, salt, soybeans, and water. The sauce is more delicious if it is made with rain water. The rice should be ‘Nep cai hoa vang’, a special variety of sticky rice of high quality and special flavor grown mainly in the northern delta and midland provinces. Cooked glutinous rice is fermented for several days in an incubation chamber. After 6 days, the rice koji, resembling soft green-lentil cake, is moved to a salt tank. It is sold in big supermarkets in provinces and cities nationwide and is exported to other Asian countries.