Dashi

 is a family of stocks used in Japanese cuisine. "Dashi" forms the base for miso soup, clear broth soup, noodle broth soup, and many simmering liquids to accentuate the savory flavor known as umami. "Dashi" is also mixed into the flour base of some grilled foods like okonomiyaki and takoyaki.
Preparation.
The most common form of "dashi" is a simple broth made by heating water containing "kombu" (edible kelp) and "kezurikatsuo" (shavings of "katsuobushi" – preserved, fermented skipjack tuna or bonito) to near-boiling, then straining the resultant liquid; dried anchovies or sardines may be substituted. The element of umami, one of the five basic tastes, is introduced into "dashi" from the use of katsuobushi and kombu. Katsuobushi is especially high in sodium inosinate and kombu is especially high in glutamic acids; both combined create a synergy of umami.
Granulated or liquid instant "dashi" largely replaced the homemade product in the second half of the 20th century. Homemade "dashi" is less popular today, even in Japan. Compared to the taste of homemade dashi, instant "dashi" tends to have a stronger, less subtle flavor, due to the use of chemical flavor enhancers—glutamates and ribonucleotides.
Variations.
Other kinds of "dashi" are made by soaking kelp, niboshi, or shiitake in water for many hours or by heating them in near-boiling water and straining the resulting broth.
History.
In 1908, the unusual and strong flavor of kelp "dashi" was identified by Kikunae Ikeda as "umami", the "fifth flavor", attributed to human taste receptors responding to glutamic acid.