Have you ever knocked back a nice tall glass of soy sauce? Me neither. Most are unbearably salty and harsh, useful only for cooking. But not all soy sauces are created equal.
This shoyu—the Japanese word for “soy sauce”—comes from Suehiro, a firm that’s been making soy sauce since 1879 in Tatsuno, Japan, about 90 minutes west of Osaka. They start with soy beans and wheat grown in Japan, plus water, sea salt, and koji to kick off the fermentation. Once the first batch of soy sauce is fully prepared, to make a “double brewed” shoyu (called "saishikomi" in Japanese), they start as if to make a new, second batch with more wheat and soy beans, but this time they replace the water and salt with the first batch of soy sauce.
The result is a naturally fermented soy sauce that’s smoother and softer and a bit thicker in texture. It’s still plenty salty, but with the harsh edges rounded off. It's great for blending into sauces; when I make a stir fry sauce with it, I usually use half double brewed soy sauce and half water—the sauce is so rich that cutting it with water still leaves plenty of flavor. It's also excellent for sprinkling at the end of cooking. In Japan, this richness of a saishikomi is saved for more luxurious dishes, such as a dipping sauce for sashimi.