dashi
Japan's basic stock, usually steeped from kombu seaweed and dried bonito flakes: clear, lightly smoky, deeply savoury.
Dashi is the foundational stock of Japanese cooking. Rather than being simmered for hours, it is briefly steeped: kombu, a dried kelp, is heated in water, then katsuobushi, paper-thin shavings of dried bonito, are left to infuse before everything is strained; vegetarian versions use kombu and dried shiitake. It tastes mild, faintly of the sea and smoke, and above all savoury, not of meat or vegetables, and it gives miso soup, simmered dishes and sauces their characteristic base note without taking over. Kombu and katsuobushi are sold in Asian grocery shops and online, as is dashi in instant granules or in tea-bag-style sachets for steeping.
Substitute:
The closest stand-in is instant dashi in granules or sachets; it is usually saltier and a little flatter, so go easy on further seasoning. For a vegetarian version, soak kombu and dried shiitake in cold water. Chicken or vegetable stock is not a good substitute: it brings its own heavier flavour, and the dish no longer tastes Japanese.