For the Dipping Sauce
In a medium saucepan, add the sake and bring it to a boil over medium high heat.
Add soy sauce and mirin, mix well then add the kombu and katsuobushi
Bring the sauce to a boil and continue to cook over a low heat for another 5 mins before removing from the heat, straining the sauce and setting aside.
For the Soba Noodles
In a large pot, boil enough water to cook the soba noodles. When the water reaches a boil, add in the noodles and cook till done. Ensure the noodles don’t stick together and aren’t overcooked.
While the noodles cook, prepare a large bowl of ice water to cool the noodles when they’re done.
Using a sieve, drain the soba noodles and rinse the noodles under cold running water to get rid of the extra starch.
Transfer the noodles in to the iced water and set aside till the noodles are cool and ready to eat.
To Serve
Make ready the hegi, or a flat bamboo sieve. Take a few strands of the noodles at a time. Loop the strands onto the sieve to make a nice little bundle. This is one portion. Allow for about 10-12 portions or so per person.
Arrange each bundle separately, to allow for easy pickup with chopsticks.
Serve directly on the hegi, or place a plate under the bamboo sieve to catch any drips. Put soba noodles and garnish with shredded nori sheet on top.
Put one part of cooled dipping sauce and 2-3 parts of iced water in a serving pitcher or small individual bowls.
To Eat Soba Noodles
First fill out a dipping bowl with diluted tsuyu, and add green onions and/or wasabi (optional). Then pick up a bundle of soba noodles at a time, dip in the tsuyu briefly, and slurp the noodles up. The dipping sauce is very salty, so don’t soak the noodles in the sauce for a long time.