Cup of Yum
1. Gather all the ingredients.
2. In a saucepan, add ½ cup sake, 1⅛ cup mirin, and 1 cup soy sauce.
3. Add 1 piece kombu (dried kelp) and 1 cup katsuobushi (dried bonito flakes).
4. Slowly bring it to a boil over medium-low heat.
5. Then, reduce the heat to low and simmer for 5 minutes. Then turn off the heat and let it cool.
6. Pass the mixture through a fine-mesh sieve. Tip: Reserve the kombu and katsuobushi for another use (see below).

To Serve

1. This Mentsuyu is concentrated. In general, the mentsuyu-to-water ratio should be 1:2 for a dipping sauce for cold Zaru Soba or Tanuki Udon and 1:4 for Udon Noodle Soup or Soba Noodle Soup. Please adjust the taste of your dipping sauce or soup broth by adding more mentsuyu or water.

To Store

1. You can store the Mentsuyu in a mason jar in the refrigerator for up to a month.

To Repurpose the Spent Katsuobushi and Kombu

1. Save the spent kombu and katsuobushi in an airtight container and store it in the refrigerator for a week or in the freezer for up to a month.
2. Repurpose the spent katsuobushi and kombu to make Homemade Furikake (Rice Seasoning).