Sobayu, the cloudy water a soba shop pours you after the noodles are gone

At a soba shop in Japan, the meal is not over when the noodles are. A few minutes after the last strands of cold mori soba leave the bamboo tray, a small lacquered pitcher arrives at the table. Many visitors leave without knowing what it was for.

What is in the pitcher

The pitcher is a yutō (湯桶). It is usually square, in red or black lacquer, with the spout set on its side. Inside is sobayu (そば湯), the water the noodles were boiled in, cloudy with buckwheat starch. Some shops stir in a spoonful of soba flour, so it pours almost like thin cream.

Sobayu comes with cold soba such as mori, zaru and seiro, because you eat those by dipping them into a separate cup of tsuyu (つゆ), the dipping sauce. Hot kake soba already sits in its broth, so there is nothing to dilute and usually no pitcher comes.

How to drink it

Pour the sobayu straight into the soba-choko, the small cup that still holds the dipping sauce. Keep pouring until the salt and dashi soften into something you would sip. Leftover negi and wasabi can go in too. Taste it, add more if it is still sharp, and drink it slowly from the cup.

If the tsuyu is gone or too strong, you can drink the sobayu on its own. Leaving the pitcher untouched is not rude either. It only means one part of the meal went unused.

そば湯を注ぐと、さっきまでのつゆが食後の一杯に変わる。

Where it tastes best

Shops that make their noodles by hand, often marked teuchi (手打ち) by the door, tend to pour the richest sobayu, and it gets thicker as the pot works through lunch. The custom is usually traced to Shinshū, the old name for Nagano, where buckwheat grows in cold highland fields. Togakushi, in the hills north of Nagano city, is a good place to try it close to where it started.