Making Dubu (Tofu)

Dubu (두부), tofu, is soy milk curdled with mineral salts. The Encyclopedia of Korean Culture explains that the bu (腐) in its name means not "rotten" but soft and yielding like brain tissue, and that Koreans also called it po (泡). For the ingredient itself, see dubu; this page covers the making.

A Goryeo arrival

Tofu came from China, though no one knows exactly when. Old Korean reference works credited its invention to a Han-dynasty prince in the second century BCE, but the encyclopedia notes that it first appears in Chinese texts only in the late Tang, which suggests a later origin. In Korea the word first shows up in a poem in the Mogeunjip, the collected works of the late-Goryeo scholar Yi Saek, so tofu probably arrived from Yuan China. By the Joseon period, the Sejong sillok records, a Ming emperor praised Korean women sent to his court for their cooking and singled out their tofu. The Encyclopedia of Korean Folk Culture adds that royal tombs had attached monasteries, called jopo-sa, "tofu-making temples," that supplied tofu for the rites (temple food).

Soaking and grinding

The method has barely changed. Both encyclopedias describe soaking dried soybeans for about half a day to a full day, until they have swelled, then grinding them with water on a millstone (today, a blender). The Encyclopedia of Korean Culture adds that tofu millstones survive in country homes, where many families still make their own.

Cooking and straining the soy milk

Next the ground beans are diluted, cooked and separated into soy milk and pulp. The Encyclopedia of Korean Culture gives the classic sequence: add about ten times the beans' volume of water, boil for 5 to 10 minutes, then pour the slurry into a cloth bag and squeeze. The liquid is soy milk (duyu); the pulp left in the bag is biji, which Koreans cook into stews or ferment into a paste (kongbiji-jjigae).

The folk encyclopedia distinguishes two orders of work. In one, the ground beans are cooked first and the pulp strained out afterward; in the other, raw soy milk is strained first and then boiled. Either way, watch the pot: soy milk foams up suddenly and scorches easily, so stir and keep the heat moderate.

Coagulants: bittern and seawater

Curdling is the critical step. The Encyclopedia of Korean Culture describes holding the soy milk at about 70 to 80°C while adding a coagulant such as calcium chloride, magnesium chloride or calcium sulfate. The traditional coagulant was gansu (간수), bittern: the salty, bitter liquid that drips naturally from damp sea salt (cheonilyeom).

Seawater works too. The encyclopedia's entry on Gangneung Chodang dubu notes that the Munjong sillok already mentions tofu curdled with seawater or salt dissolved in water. In Gangneung, Chodang village is famous for using seawater instead of bittern; the entry explains that East Sea water is rich enough in magnesium and calcium to set soy milk without being concentrated first. A popular story credits the village's tofu to the Joseon scholar Heo Yeop, whose pen name was Chodang, but the encyclopedia stresses that no document supports it. Treat it as a legend.

Sundubu, modubu and the press

What happens after the curds form decides the kind of tofu.

• Sundubu (순두부): the soft curds ladled out before pressing. Both encyclopedias note that households ate it warm with a seasoned soy sauce while the main batch was still being made; it is also the base of sundubu-jjigae. See sundubu.
• Modubu (모두부): firm block tofu. The curds are poured into a cloth-lined wooden mold, covered, and weighted (traditionally with a stone) to drive out whey, then cut into blocks once set.
• Yeondubu (연두부): silken tofu, set without pressing.

The Gangneung entry gives one Chodang method in detail: strain the ground beans, boil the soy milk at 98 to 100°C, cool it to 80°C and add seawater to form sundubu, then press for about 20 minutes in a cloth-lined box for modubu. The folk encyclopedia also records older textures, such as coarse cotton-bag tofu and fine silk-bag tofu, named for the cloth used to strain them.

At the table

Fresh tofu is best eaten the day it is made: warm sundubu with soy sauce, sliced modubu with kimchi (dubu-kimchi), or pan-fried slices (dubu-buchim) and braises (dubu-jorim). Keep homemade tofu refrigerated, covered in fresh water changed daily, and use it within a few days. Soy is a common allergen; see allergens in Korean food.