Upgrade Everything You Cook With Japanese Shoyu

The lazy Susan next to my range has witnessed my shifting condiment obsessions over the years. There was the extra-virgin olive oil phase, then the wide world of vinegar phase. Lately it has been filled with bottle after bottle of soy sauce. I have bottles of sweet Indonesian soy and Chinese mushroom soy, but my real love is Japanese shoyu. I can never go shopping at Mitsuwa Marketplace, the Japanese food market near me, without picking up a bottle. I research quickly on my phone to find a brand that is new to me and promises to be richer, mellower, more fruity or more complex from barrel aging. Shoyu has become a key part of my cooking; here’s how you can use it in your kitchen. 

What is shoyu?

Shoyu is simply the Japanese word for soy sauce, but the word implies it will be naturally brewed, fermented and aged. Shoyu is produced from mashed beans and wheat cultured with Japan’s favorite fungus, Aspergillus oryzae, a.k.a. koji, then mixed with salt brine and then stashed in a tank for a good year to ferment. Depending on the beans, the wheat, the ratio of the two, the amount of salt, the temperature, the composition of the tank and maybe even the work of wood sprites, it will develop into a soy sauce with flavors from caramel and chocolate to even apricot and sea water. 

What are the types of shoyu?

There are two basic kinds of shoyu. Koikuchi (which means “thick taste”) offers what we look for in that trustworthy bottle of Kikkoman: dark color, round flavor, and a salt level that is pronounced but doesn’t chap your lips. There is also usukuchi (“thin taste”) that is limpid in color but packs a salty wallop. Cooks from Osaka and western Japan use it more in recipes; they also use more sugar, which makes sense in terms of balance. 

What is tamari?

There’s a third type, which isn’t considered shoyu in Japan but is related to soy sauce, and that’s tamari. Originally made as a byproduct of miso manufacturing, it is made without wheat (or with very little; don’t assume it is gluten-free unless labeled as such) and fermented for at least a year and often longer. It is darker, richer, broader — not a voice in your cooking as much as a chorus. 

How do you cook with shoyu?

This gets us to the essential duality of shoyu: It is a cooking ingredient as well as a condiment. It figures into nearly every stew and simmering sauce (alongside its usual company of sugar, mirin and sake) but it also gives backbone to dipping sauces. Cubes of sweet Japanese pumpkin (kabocha) simmered in dashi broth seasoned with koikuchi shoyu, sake and sugar are terrific; you can taste every ingredient in the flesh. Usukuchi shoyu added at the last instant to stir-fried cabbage is bright and lively. 

Maybe it’s because I lived outside of Osaka, but I’m a devotee of Kikkoman’s usukuchi, which I buy in big bottles and go through regularly while cooking. I use it not just in Japanese dishes, but literally anything that needs more salt and body. It is the only reason people compliment me year after year on my turkey gravy. For something special — a soy sauce that you can taste from a spoon — I love Higeta Honzen, a koikuchi soy sauce that’s been double-brewed for a wound-up intensity that just opens up on your tongue. Mix it with some bottled yuzu juice for the best ponzu you’ll ever try. 

The flavor and color of soy sauce changes when left at room temperature. I use them quickly, but if you don’t then keep your best bottles in the fridge. Once you start experimenting, you may accrue quite the stash. Just saying.