Step 1

Gather all the ingredients.

Step 2

Combine all the ingredients in a sterilized mason jar and mix well.

Step 3

Steep in the refrigerator overnight (minimum), for several days, or for up to a week. Some restaurants steep for a month, especially if you make a big batch.

Step 4

After steeping, drain over a sieve to get rid of katsuobushi and kombu. You can use leftover kombu and katsuobushi to make homemade furikake (Japanese rice seasoning).