Prepare the buckwheat soba noodles, the main ingredient for the soba.

Soba
How to make authentic Japanese-style Soba and a savory Soba dipping sauce (Tsuyu).
What You'll Need
Instructions
Prepare the natto to add a nutty flavor.
If using mushrooms, substitute with other mushrooms and blanch them briefly.
Prepare the Nagaimo and yam, and use kelp water that has been soaked with kelp in the refrigerator from the previous day.
Add the anchovy broth to a pot and start boiling.
Boil the anchovy broth over low heat for about 5 minutes, skimming off the foam.
⏱️ 5m 0sPlace the prepared natto in a bowl.
Pour the boiled anchovy broth into a bowl to prepare the hot broth.
Add mirin to the hot anchovy broth to let the alcohol evaporate.
Mix the anchovy broth, mirin, Jin-ganjang, and Hondashi to complete the soba sauce.
Boil the noodles in boiling water.
While the noodles are boiling, add hot water and boil for another minute.
⏱️ 1m 0sBoil for 3 more minutes to cook the noodles completely.
⏱️ 3m 0sRinse the boiled noodles in cold water to bring out their chewy texture.
Place the boiled noodles in a bowl and top with the prepared natto, yam, green onion, and red chili powder.
Pour the finished soba sauce over the top to finish.