|Like many traditional Japanese food manufacturers, the freeze-dried tofu shops owe their unique way of life to their Chinese neighbors. According to William Shurtleff, co-author with Akiko Aoyagi of several books on traditional Japanese foods, frozen tofu was probably first made in the cold mountainous regions of northern China about 1,000 to 1,500 years ago. It was found that if tofu was left out in the snow overnight until frozen solid, it underwent a radical transformation. When later placed in warm water, the tofu thawed, leaving a fine-grained, highly absorbent food that had the texture of tender meat.
Although Chinese frozen tofu had vast culinary potential, it had two drawbacks. First, it had to remain frozen or, like fresh tofu, it would spoil due to bacterial action. Second, like ice, it was heavy and difficult to transport.
Leave it to the Japanese to make a good thing better. About 1225 A.D., in a temple on Mount Koya, near Kyoto, a Buddhist monk began drying frozen tofu in a heated shed. This new "dried food" came to be known as koya dofu. Because it contained little water, it kept for several months without spoiling. The relentlessly utilitarian Japanese mind, however, was still not satisfied. In the fifteenth century, aggressive warlord Takeda Shingen recognized koya dofu's potential as a military ration. To make the process more mobile, Shingen did away with the heated shed and simply let the frozen tofu dry in the sun for a few weeks. This kori (frozen) dofu, named thus to distinguish it from the monk's version, was virtually imperishable.