Canned or boxed vegetable broth may have its uses, but I’m of the opinion that you’re better off using plain water if you don’t have the homemade stuff on hand.
Yet I still sometimes resent the extra work and foresight that homemade stock requires: Saving all those vegetable trimmings. Simmering. Cooling. Straining. Portioning out. Dispensing with the spent solids. Freezing. Then remembering to thaw before I need to cook with it.
Dashi, however, requires none of that. Just cover kombu with water and let it sit. That’s it. No chopping, no simmering, no skimming, and, usually, no straining. Traditionally it’s made from both kombu (kelp) and bonito flakes (shaved dried fish), but for vegetarian versions, the bonito can be omitted or replaced with dried shiitake mushrooms. The result has a saline quality and is umami-rich, with a slightly fuller consistency than stock or plain water.
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Even without the bonito flakes, dashi is surprisingly rich in umami, in part because kombu contains some of the same naturally occurring glutamates that appear in MSG. My recipe includes both cold and hot water methods—the cold water method produces a better-tasting dashi, with a fuller flavor, but when you haven’t been able to plan ahead, the hot water method will work fine.
Dashi is the basis of miso soup, of course, and more importantly, one of the building blocks of Japanese cuisine. I always use it in my vegetarian ramen recipes: a spicy one with light miso, chili flakes, and rich soy milk; a zingier one made with a slurry of ginger, scallions, soy sauce, and a few drops of toasted sesame oil; and in cold noodle dishes like zaru soba, too, where it’s seasoned with mirin and soy sauce.
Or sometimes, I’ll add a square of kombu to my usual pot of vegetable stock once I’ve taken off the heat and leave it there to cool; this adds a layer of extra umami richness. When I don’t have homemade stock at hand, dashi steps forward: in hot and cold soups of various cuisines, in rice pilaf and risotto, as a braising or poaching liquid, and in dressings, marinades, and sauces.
Dashi works perfectly well in savory-veg forward (i.e. not too sweet) smoothies, too—wherever you might use coconut water or plain water. And this may sound crazy, but that zing of mirin in zaru soba also make me wonder if dashi’s mild tannins, which give it a tea-like quality, could be fun for a mixologist, pairing clear kombu stock with grape-based spirits or, of course, sake.
And don’t toss the rehydrated kombu—chopped up, it’s a nutritious addition to salads and bowls of rice and other grains.
Dried kombu has its uses, too. I recently learned from Danny Bowien of Mission Chinese to grind up dried kombu with dried shiitake mushrooms for a homemade approximation of the Taiwanese seasoning “mushroom powder”—this is a flavor bomb for vegetarian dishes like his Mapo Tofu. For homemade spice blends, using kombu in this way adds savoriness without salt.
Okay, I’ll stop there. But when was the last time a can of vegetable broth got you this excited?