Yamakake Soba (山かけそば, soba with grated mountain yam)

Ingredients

Equipment Needed

• •Oroshigane (Japanese grater), or the finest face of a box grater
• •Suribachi (ridged grinding bowl), optional for very smooth tororo
• •Fine-mesh strainer lined with a clean cloth
• •Zaru (bamboo draining basket), or a colander

Instructions

1. 1

   Steep the konbu

   Wipe the konbu with a damp cloth, but don't wash it. Put it in the cold water and bring it up slowly over low heat, ten to fifteen minutes. Pull the konbu when the water trembles and small bubbles climb the sides of the pot, before it boils.

   That pale dust on the konbu is flavor, not dirt. Boiling the kelp makes the stock faintly bitter and slick, so the rule is only the shortest way to say protect the clarity.
2. 2

   Finish the dashi

   Bring the water to a gentle boil after the konbu is out. Add the katsuobushi all at once, take the pot off the heat, and leave it alone until the flakes sink, two or three minutes. Strain through a cloth or fine sieve and let it drip naturally. Don't squeeze.

   Squeezing presses stronger, oily flavors from the flakes into the stock. For this bowl, clear dashi matters because the tororo softens everything it touches.
3. 3

   Season the broth

   Measure about 3 cups of dashi back into the pot. Add the shōyu, mirin, and sugar, then simmer for one minute so the mirin loses its raw edge. Taste it. The broth should be a little more seasoned than you expect, because soba and tororo will quiet it in the bowl.

4. 4

   Grate the yam

   Peel only the yam you need and grate it just before serving on an oroshigane, a Japanese grater, or the finest face of a box grater. Stir the tororo until glossy. If using dense yamaimo or jinenjo, loosen it with 1 to 2 tablespoons of the seasoned broth. If using loose nagaimo, leave it nearly as it is.

   The yam may make your hands itch. That's common with raw nagaimo, so use gloves or hold it with a towel. Fresh tororo should smell clean and faintly sweet, never sour.
5. 5

   Cook the soba

   Boil the soba in plenty of unsalted water, stirring once as the noodles go in. Cook according to the package timing, then taste a strand. It should be tender but still springy. Drain and rinse under cold running water, rubbing gently with your hands until the surface starch is gone and the noodles feel clean.

   Rinse soba even when the bowl will be hot. Starch left on the noodles clouds the broth and makes the tororo feel heavy instead of clean.
6. 6

   Assemble the bowls

   For hot yamakake soba, dip the rinsed noodles back into hot water for ten seconds, drain well, and divide them between warmed bowls. Ladle the hot broth around the noodles, then crown each bowl with tororo. For cold service, chill the broth, chill the rinsed noodles thoroughly, and use a little less broth in each bowl. Finish with scallion and nori, and add wasabi on the side if serving cold. Slurp without apology; it pulls broth and tororo through the soba together.

Chef Tips

• •Choose nagaimo or yamaimo that feels heavy and firm, with no soft spots or sour smell at the cut end. The cut face should look moist and clean. If the ingredient is tired, nothing good happens later.
• •Don't grate the yam ahead for convenience unless you must. Thirty minutes under plastic wrap in the refrigerator is survivable; several hours is not. Fresh tororo has lift and brightness.
• •For a meatless table, make dashi from 10g konbu and 2 dried shiitake soaked overnight in the same amount of water, then warmed and strained. That's honmono in the temple-kitchen line, not a compromise.
• •Instant dashi granules make a salty bowl quickly, but here the broth is part of the dish. Make the dashi ahead instead. Weeknight cooking is allowed to be sensible.

Advance Preparation

• •The dashi or fully seasoned broth can be made up to two days ahead and refrigerated. Reheat it gently for hot soba, or chill it well for cold service.
• •The konbu can soak overnight in the measured water before heating, which gives a rounder stock and makes the cooking faster.
• •Cook soba just before serving. Once boiled and rinsed, it loses its spring quickly.

Frequently Asked Questions

Nutrition Information

1 serving (about 780g)