Tofu

Tofu (豆腐, dòufu, literally "bean curd") is a food made by coagulating freshly boiled soy milk and then pressing the resulting curds into solid white blocks. The process is analogous to cheesemaking: soybeans are the equivalent of milk, nigari (magnesium chloride, a natural byproduct of sea salt production) or calcium sulfate acts as the coagulant, and the resulting curds are shaped and pressed to produce tofu in various consistencies from silken to extra-firm.

The production process begins with soaking dried soybeans overnight, then grinding them with water, boiling the mixture, and filtering out the insoluble pulp (okara, 豆渣, dòuzhā) to produce soy milk. The coagulant is stirred into the hot soy milk, causing it to separate into curds and whey. For silken tofu (嫩豆腐, nèn dòufu), the curds are not pressed, resulting in a smooth, custard-like texture. For firm and extra-firm tofu (老豆腐, lǎo dòufu), the curds are pressed under weights to remove more whey, producing a denser, chewier product.

Tofu originated in China during the Han dynasty (206 BCE-220 CE), traditionally attributed to the Prince of Huainan, Liu An (刘安). From China, tofu spread to Japan (where it became a cornerstone of Buddhist vegetarian cuisine, shōjin ryōri), Korea, and eventually throughout East and Southeast Asia. As a complete protein containing all essential amino acids, tofu was historically crucial as a source of nutrition in East Asian diets, particularly for Buddhist monks who observed vegetarian dietary precepts. Tofu's mild flavor and adaptability make it a canvas for countless preparations.

The versatility of tofu in East Asian cuisine is extraordinary. Silken tofu is used in soups (like miso soup or hot and sour soup), chilled as a summer appetizer (hiyayakko in Japan, with ginger and soy sauce), or blended into smoothies and desserts. Firm tofu is cut into cubes and stir-fried, deep-fried, braised in savory sauces (mapo tofu, 麻婆豆腐, being the most famous example), or grilled (yaki-dofu). Tofu is also processed into fermented products: fermented tofu (腐乳, fǔrǔ), also known as "Chinese cheese," is a pungent, salty condiment aged in brine with rice wine and spices; tofu skin (腐竹, fǔzhú) is the thin film that forms on the surface of heated soy milk, dried into sheets or sticks used in stir-fries and hotpots. Nutritionally, tofu is an excellent source of protein, calcium (especially when set with calcium sulfate), iron, and isoflavones, which have been studied for their potential health benefits including reduced risk of heart disease and certain cancers.