Learn how to make Kombu Dashi, vegan-friendly Japanese soup stock, at home and create the umami flavor for your Japanese dishes!
Gather all the ingredients. Most Japanese recipes would say to gently clean the kombu with a damp cloth. However, these days, kombu is pretty clean so just make sure it doesn't musty. DO NOT wash or wipe off the white powdery substance (Mannitol), which contributes to the umami flavor in dashi.
Make a couple of slits on the kombu, which will help release more flavor.
Put water and kombu in a large bottle.
Put the cap on and let it steep on the counter for 2-3 hours in the summertime and 4-5 hours in the winter time. You can also cold brew kombu dashi overnight in the refrigerator.
Remove the kombu from the bottle and reserve the used kombu (see below). Kombu dashi is now ready to use. If you are not using the dashi right away, save it in a bottle and keep in the refrigerator for 4-5 days or in the freezer for 2 weeks. I recommend using it sooner for the best flavor.
In a medium pot, put the kombu and water. [optional] If you have time, soak for 3 hours or up to a half day ahead of time. Kombu’s flavor comes out naturally from soaking in water.
Turn on the heat to medium-low heat and slowly bring to almost boil, about 10 minutes.
Meanwhile, clean the dashi by skimming the surface.
Just before the dashi starts boiling, remove kombu from the pot (see below for what to do with it). If you leave the kombu inside, the dashi will become slimy and bitter.
Now kombu dashi is ready to use. If you are not using the dashi right away, save it in a bottle and keep in the refrigerator for 4-5 days or in the freezer for 2 weeks. I recommend using it sooner for the best flavor.
Recipe by Namiko Chen of Just One Cookbook. All images and content on this site are copyright protected. Please do not use my images without my permission. If you’d like to share this recipe on your site, please re-write the recipe and link to this post as the original source. Thank you.