Sweet bean sauce (Chinese: tianmianjiang; also known as sweet bean paste, sweet soybean paste, sweet flour sauce, or sweet noodle sauce) is a thick, dark brown- or black-colored Chinese sauce made from wheat flour, sugar, salt, mantou flour, and fermented yellow soybeans (the lees left over from the fermentation of soybeans to make soy sauce).
There are many different types of sweet bean sauces depending on the different compositions and the different method of production, and each variation represents the unique local style of a particular region, and even within the same geographical region, different manufacturers produce different kinds of sweet bean sauce. For example, in northern China, the use of sugar is far less than in southern China in terms of the amount added, while the usage of mantou flour as the main ingredient is a much more common practice. Traditionally, in these regions, a good brand of sweet bean sauce is considered top quality when its sweet taste results not from the addition of sugar, but as a direct result of the fermentation of the starches contained in the sauce's ingredients.
Sweet bean sauce can be found in typical Asian supermarkets under various English names, but with a common Chinese name (甜麵醬). Sweet bean sauce's Korean equivalent is the chunjang (hangul: 춘장; hanja: 春醬) used in the dish jajangmyeon (hangul: 자장면; hanja: 炸醬麵).
Chunjang (춘장) (or Choonjang or Chunzang or Choonzang or Chinese soybean paste or Chinese bean paste < HS code: 2103.90.1020 >)