Dashi is the basic broth used in all manner of Japanese soups, stews and sauces. It’s as fundamental to Japanese cooking as a basic meat broth is to cooking in the West. To make dashi, a whole bonito (a relatively small tuna-like fish) is dried and smoked until it resembles a hardened, dark brown banana. This process takes about a year. Once the dried bonito is in hand, it is shaved with a device that looks a little like a shoebox but with a razor sharp blade running across the top. The bonito is shaved on the box, much like potatoes are sliced on a mandolin or a plastic Japanese slicer.
Dashi is best prepared just before serving (including the shaving of the bonito). To begin the broth, take a 12-inch length (for a quart of dashi) of konbu (giant seaweed) and put it in a pot with a quart of cold water. Slowly bring to the simmer. When the simmer is reached, take out the konbu. Add a large handful of bonito flakes—that you’ve either shaved yourself or bought in a plastic bag–to the broth, off the heat, and let infuse for one to two minutes. Strain.
Dashi has a distinct smoky taste and delicate sea-like flavor that make it useful for any number of seafood dishes, Japanese or otherwise. Eric Ripert, the chef at Le Bernardin, in New York City, does a number of interesting things with dashi. He once served what tasted like dashi with lime juice—the juxtaposition of tart and smoky was delicious—that had then been clarified like consommé. I also once had a cold fish dish, set on a round of dashi that had been set with, I assume, gelatin or possibly agar. Keep in mind, also, that dash is the base for miso soup. To make miso soup, just whisk a little miso into dash and you have it.