The Japanese soup stock made from dried bonito and kelp is dashi.
Dashi is a foundational Japanese stock used in miso soup, clear soups, noodle broths, simmered dishes, and savory foods such as okonomiyaki and takoyaki. The classic version combines kombu, an edible kelp, with katsuobushi, thin shavings of dried and fermented skipjack tuna or bonito. The ingredients are steeped or heated in water, and the liquid is strained.
The pairing works because kombu supplies glutamic acids while katsuobushi supplies inosinate. Together, they create a strong umami effect. Dashi is therefore not the same thing as miso soup: miso soup is a finished soup whose broth commonly includes dashi. Other varieties use dried sardines or anchovies, dried shiitake mushrooms, or kombu alone, so the word refers to a family of Japanese stocks rather than one single recipe.
Instant granules and liquid concentrates became especially common in Japan during the second half of the 20th century, although cooks still make dashi from dried ingredients when they want a subtler flavor.