Japanese Dashi Broth

Dashi is an incredibly simple fish broth and it forms one of the culinary cornerstones of Japanese cooking. It's made in about 10 minutes with just three ingredients: water, kombu (dried kelp), and katsuobushi or bonito flakes (dried and smoked skipjack tuna that is shaved into thin flakes). The resulting clear broth forms the base for miso soup, noodle broth and many kinds of simmering liquid.  Kombu is rich in glutamic acid while katsuobushi is especially high in inosinic acid, with the synergy effect identified as a source of umami, one of the five basic tastes in Japan, besides sweetness, sourness, saltiness and bitterness .

There are also other ingredients for making homemade dashi broth like dried iriko or niboshi (anchovies/sardine) or dried shiitake (mushroom) but the most common fish based stock is made from a combination of kombu and katsuobushi/bonito flakes, a basic all-purpose stock and 80% of most cooking this goes well with this dashi. Dashi stock made from these dried ingredients creates a savory umami flavor so you don't need to season the food much. These days, you can also find granulated or liquid instant dashi sold in supermarkets but it tend to have a strong and less subtle flavor than the homemade one.

The best buy of dried kelp or kombu comes from Hokkaido, namely, the hidaka-kombu and rausu-kombu and rishiri-kombu, dried and cut into sheets. The powdery crystals clinging to the surface of the seaweed contains glutamate and when dissolve in the water, give the dashi much of its umami flavor. Bonito flakes in packs are available easily in Japan, in various prices depending on the process of drying and smoking the tuna. The best striped tuna comes from Shizuoka, Miyagi, Mie and Miyazaki.

How to make dashi broth with kombu and bonito flakes?

First broth
1. Soak kombo in a four-cup (800ml) water in a saucepan.
2. Set over medium heat and remove the kombu before the water comes to a full boil
3. Add bonito flakes and simmer for about 1 minute
4. Remove the pan from heat and let the bonito flakes steep in the broth for an additional 5 minutes before straining the broth
The broth can be used immediately or refrigerated up to a week

Second broth

(remaining resultant liquid that is less subtle but can still be used for home cooking)

Add additional two cups of water (400ml), pouring through the strained kombu and bonito flakes and set over medium heat for 4-5 minutes and then strain the broth.