Yudofu (Tofu Warmed in Kombu Water)

Variations

• Ureshino onsen yudofu: in Ureshino, Saga, it is cooked in mildly alkaline spring water. The alkali dissolves the surface of the tofu, the broth turns milky and the tofu goes soft enough to melt. At home it is imitated with about 1/2 teaspoon of baking soda per litre of water; more than that tastes of soap.
• With vegetables: Chinese cabbage, chrysanthemum greens, leek and shiitake often go in. It turns into a hot pot, and the clean taste of the Kyoto tofu-only version blurs.
• Temple style: the shops outside Kyoto's temples leave out the katsuobushi and make the sauce from kombu alone — a table with neither meat nor fish.
• With cotton tofu: pressed momen tofu is firmer than silken, breaks less as you lift it, and tastes more of soy.

Tips

• The water decides the tofu. Mapo tofu blanches its tofu in salted water and explains why: "The gel was stood up by ions in the first place, so a salted bath firms the surface rather than working against it, while plain boiling water pulls soluble solids out of something that is mostly water and leaves it tasting washed." That tofu is going into a sauce, so its surface needs to be firm. The tofu in yudofu is lifted out of its water and eaten as it is. So the water is plain with kombu, and the aim is not firmness but a tremble.
• Never boiled, because of the tofu. In boiling water tofu tightens further, squeezes out water and pits inside with small holes, going spongy. Stopped just short of the boil, the tofu only warms and its texture stays. The sway is the sign it is warm to the middle.
• Never boiled, because of the kombu as well. Stocks and broths says of kombu: "Boiling brings out sliminess and bitterness." An ordinary stock lifts the kombu out before the boil. Yudofu keeps it in the pot the whole meal. So the whole pot has to stay just below the boil, and that one temperature protects both the kombu and the tofu.
• The kombu goes underneath. The bottom of the pot is the hottest place. The kombu sits between it and the tofu, so the tofu neither sticks there nor boils there on its own.
• Silken or cotton comes down to pressing. Douhua separates itself from tofu with "Pressing is the only thing that separates them." Unpressed silken tofu is the softest and breaks most easily; cotton tofu is the other way round.
• Keep the sauce warm and the tofu stays warm. In Kyoto the sauce cup stands in the middle of the pot and heats with it. Dip into cold sauce and the temperature you worked to hold drops at once.