Black bean paste

Black bean paste, commonly called "dòushā" () or "hēidòushā" (), is a sweet bean paste often used as a filling in cakes such as mooncakes or "doushabao" in many Chinese and Taiwanese cuisines.
Black bean paste is made from pulverized mung beans, combined with potassium chlorate, ferrous sulfate heptahydrate () crystal (which in Indonesia is known as "tawas hijau", or "green crystal"), or black food colouring.
Black bean paste is similar to the more well-known red bean paste. The recorded history of black bean paste goes as far back as the Ming Dynasty. 