Ingredient In-Depth: Let me Shoyu!

 

Soy in Asia is just about everywhere and in most everything. It's as solid a staple as starches like rice or wheat, and while not as popular a protein choice as pork, it's pretty prevalent.

What I wanted to expand upon is geared more toward Shoyu-醤油(JPN)/Jiangyou-醬油(CHN)/Ganjang-간장(KOR)/Soy sauce, so I have to start at the beginning, and detail some of how it's made. The key ingredient is the koji mold, or aspergillus oryzae, which occurs naturally on rice, and has been utilized for thousands of years in various applications. 

Japanese-style, the process of making soy sauce (and often miso too, because the technique is similar) is fairly simple. Steam your soybeans, combine with some (usually) toasted wheat, add some koji spores, and set it in a high-humidity environment for a few days until the koji multiplies and it all gets a little fuzzy.

That's the base. It gets mixed with salt and water to make a mash (諸味/moromi, a term also used for the mash used in brewing sake), then it hangs around for as many months or years as you've got. To keep air contact more even, it gets regularly stirred, too.

Once the brewer's intended fermentation period is up, the moromi will be (in cheesecloth, muslin, or other porous thing) packed, racked, stacked, and pressed. What comes out of the mash under that pressure is the baseline raw soy sauce, that's then gently cooked to stop the fermentation process, which presumably also helps stabilize the flavor to some degree.

That's soy sauce in brief. Now for some common variants.
In Japan, you're likely to see these:

• Tamari, made the same way but without the wheat- thus, gluten free
• Usukuchi / 'Light' soy sauce 
• Koikuchi / 'Dark' soy sauce (The common Western supermarket stuff)
• Shiro / 'White' soy sauce, made with more wheat for a lighter color

In China, Hong Kong, or Taiwan, you may be more likely to see:

• Light soy sauce (Comparable to the Japanese Koikuchi for utility, if not exact flavor)
• Dark soy sauce (Often sweetened with something, this is Very Intense, and it stains hard)

China being as big a place as it is, these vary extremely widely in flavor from region to region, so from a practical perspective it's often easier to look for a particular brand with the flavor you're looking for rather than roll the dice.

Soy sauce in China is most highly regarded coming from the provinces around Shanghai. Not only are they home to the best soy sauce, but also things like Jinhua cured ham, Zhenjiang "Black" vinegar, and other fermented culinary fundamentals of regional Chinese cuisine. Historically, this area has the fermentation and preservation bit really dialed in- though other areas have their own specialties, like the Doubanjiang/豆瓣酱 so intrinsic to the food of Sichuan (another soy product, something akin to a coarse miso fermented with chilis and other flavorants).

Now I could go a fair bit longer about the more adulterated variations, such as the Indonesian sweet soy kecap manis, or the more vigorously flavor and aromatic-infused soy sauces you often see in the already complex Sichuan cuisine, but I don't want to lose the few readers I have, so that will be for another day.