It’s not certain exactly when tofu was introduced to Japan. One theory holds that it was brought over from China by the great Buddhist priest and scholar Kukai, also known as Kobo Taishi (734-835) in the early ninth century during the early Heian Period (794- 1185). However, we must fast-forward to the Kamakura Period (1185-1333) to find any written reference to a food that we now take for granted in Japan.
In any case, tofu was a luxury food reserved for the upper classes until the mid-Edo Period (1603-1868). Around the mid-18th century, tofu became an affordable and popular food in the cities, especially Edo (old Tokyo), becoming so ubiquitous that its price was strictly regulated by the Tokugawa shogunate. In 1782, a cookbook with 100 tofu recipes, called “Tofu Hyakuchin,” was published in Osaka. It became a national best-seller, leading to two sequels, and the original is still in print, in both old and modernized Japanese.
Tofu in Japan is made by grinding up water-logged soy beans, cooking the resulting slurry, separating the solids (called okara) and the liquid (tōnyū, or soy milk), and solidifying the latter with a coagulant. The coagulant used in Japan is nigari (magnesium chloride), which is derived from sea water. Different kinds of tofu are made by varying how much water is drained away from the soy milk.
The most widely used tofu type, called momen (cotton) tofu, is made with the least amount of water — the soy milk curds that are the result of the coagulation process are put into a mold lined with a porous fabric and pressed to form a block.
Kinugoshi “silk-filtered” tofu, meanwhile, is made by putting the curds, which have been stirred very gently so that they remain smooth, into a mold, where they are allowed to set. The result is softer and contains more water. The name “silk-filtered” is a bit misleading, since it refers to the silky smooth texture of the product rather than the manufacturing process, which does not involve silk in any way.
Another type of tofu that’s not as well known is oboro dofu, which is made by scooping up the curds and putting them into molds, which can be round or square, and allowing them to drain off naturally without being pressed.
The easiest no-cook summer dish to put together is hiyayakko, which is simply a block of tofu topped with various yakumi condiments such as chopped green onions, thinly sliced myōga ginger, grated ginger or wasabi, finely julienned shiso (perilla) leaves and bonito flakes, with soy sauce drizzled over the whole dish.
In the Edo Period, hiyayakko was cooled with well water for the rich and members of the aristocracy, but nowadays we commoners naturally rely on the modern refrigerator. To serve unheated tofu, it must be impeccably fresh, so be sure to note the expiry date, and to transport it quickly to your refrigerator after purchase (especially in the summer heat).
Once the sealed package is open (or if the tofu comes from a traditional shop and is not sealed), transfer it to a container with a strong, reliable sealing lid or a bowl covered with plastic wrap, and be sure to change the water in which the tofu sits at least once a day. Chilled tofu should be eaten within two to three days of purchase.
Another way to enjoy chilled tofu is to marinate it. The tofu I’ve used in this version of the Italian classic insalata caprese is marinated in shio-kōji, salted rice malt, a traditional seasoning that’s had a surge in popularity in the last few years.
Marinating the tofu makes its texture denser and creamier, and adds umami and saltiness. Since the tofu is already seasoned, go easy on the salt.
Caprese-style salad with shio-kōji marinated tofu
1 small tofu block (300g)
3-4 tablespoons prepared shio-kōji (salted rice malt)
1 medium size ripe avocado
4 medium size ripe tomatoes
12-15 fresh basil leaves
coarse sea salt or fleur de sel
freshly ground black pepper
4 to 5 tablespoons extra virgin olive oil
Begin to prepare the tofu two to four days before you plan to serve the salad. Start by draining the tofu, and then wrapping it in two layers of paper towel. Place on a plate and microwave on the high setting for two minutes. Drain, and then leave it to cool. Next, put 1 tablespoon of shio-kōji in a plastic container, and place the well-drained tofu on top. Spoon the rest of the shio-kōji onto the tofu. Close the plastic container and refrigerate for two to three days, draining away the excess water that comes out of the tofu once a day. And remember: The longer it marinates, the stronger the flavor will be.
When you’re ready to serve the salad, scrape off the shio-kōji and slice the tofu. Pit, peel and slice the avocado. Slice the tomatoes, and rip up the basil leaves.Arrange the avocado and tomato slices on four serving plates and top the dish with the tofu slices and basil. Sprinkle lightly with salt and pepper, drizzle with olive oil, and enjoy!