Dashi is a clear soup base in Japanese cooking. You make it by soaking or briefly boiling seaweed, dried tuna flakes, dried mushrooms, or a mix of these, then keeping the liquid and throwing the solids away. The point is to pull the taste out of those things. A good dashi looks light and clear, not thick like a Western meat stock; you notice a deep, round taste more than you notice fish or seaweed. It sits under miso soup, noodle soup, and many simmered dishes — in a Japanese kitchen it is as basic as chicken stock is in many others. Home cooks often use instant dashi powder or granules; that is still called dashi. English keeps the Japanese word rather than translating it as “stock.”