Soy Sauce

Soy Sauce is a staple ingredient for cooking throughout Asia though it originated in China. 

Soybeans are cooked; mixed with flour and a specific mold as well as salt; covered in water and allowed to ferment. Sometimes other things are added like sugar, alcohol and caramel color. 

There are regional differences of course. Japan generally uses more wheat flour to create their preferred flavor profile. Though they also produce wheat free tamari soy sauce. Indonesia uses a thicker and stronger soy sauce and so on.

For China, there are primarily three soy sauce types: Light or Thin, not to be confused with Lite or reduced sodium; Dark, Black or sometimes Thick soy; and a Mushroom variety of Dark soy sauce.  There is a Thick soy that's different from Dark soy as well, but it's not commonly encountered.

Wikipedia summarizes their characteristics well:

• Light or fresh soy sauce (生抽 shēngchōu or 酱清 "jiàngqing") is a thin (low viscosity), opaque, lighter brown soy sauce. It is the main soy sauce used for seasoning, since it is saltier, has less noticeable color, and also adds a distinct flavour. The light soy sauce made from the first pressing of the soybeans is called tóuchōu (simplified Chinese: 头抽; traditional Chinese: 頭抽), which can be loosely translated as first soy sauce or referred to as premium light soy sauce. Touchōu is sold at a premium because, like extra virgin olive oil, the flavor of the first pressing is considered superior. An additional classification of light soy sauce, shuānghuáng (雙璜), is double-fermented to add further complexity to the flavour. These last two more delicate types are used primarily for dipping.
• Dark and old soy sauce (老抽 lǎochōu), a darker and slightly thicker soy sauce, is aged longer, contains caramel, and may contain added molasses to give it its distinctive appearance. This variety is mainly used during cooking, since its flavour develops during heating. It has a richer, slightly sweeter, and less salty flavour than light soy sauce. Dark soy sauce is partly used to add color and flavour to a dish after cooking, but, as stated above, is more often used during the cooking process, rather than after.
  • Mushroom dark soy (草菇老抽 cǎogū lǎochōu): In the finishing and aging process of making dark soy sauce, the broth of Volvariella volvacea mixed into the soy sauce and is then exposed to the sun to produce this type of dark soy. The added broth gives this soy sauce a richer flavour than plain dark soy sauce.

Going through my various cookbooks and looking for recommended brands these are the results.

Light Soy Sauce

Kikkoman is the first pick of Grace Young and Barbara Tropp. Tropp also likes the reduced sodium Kikkoman. While Kikkoman has a wheatier, sweeter profile than most Chinese soy sauce it is nearly universally available and quite compatible in the role of Light Soy Sauce. I've used plenty of Kikkoman in the past. It's a fine product but I prefer more Chinese-oriented flavor profiles over this.

Koon Chun Thin Soy Sauce is an equal pick for Eileen Yin Fei Lo and Bruce Cost's recommended brand. I've done some testing with this brand and it is a quality brand. Good complexity and nuanced flavors. High salt content for my situation though. If you use this soy sauce, pay special attention to balancing flavors as you finish the dish. Use less if cooking from my recipes as it will be overly salty. Alternatively, you can increase other flavorings to bring it into balance as well, but that's a trickier path. 

Pearl River Bridge Superior Light Soy is an equal pick of Bruce Cost and respected by Barbara Tropp though she prefers Kikkoman. This soy is often recommended on the internet and is the soy sauce I've used for some years now. It's lower in sodium than most other brands which is one reason I use it. Beware though, the bulk plastic jugs of this soy sauce are rated about 600 mg/tablespoon more sodium per tablespoon than the glass bottled soy with the same label. I don't know why. My recipes are based around this brand.

Yuet Heung Yuen Soy Sauce is preferred by Eileen Yin Fei Lo and Mai Leung. I've not noticed this sauce in a local store yet.

I did a taste test of Koon Chun, Pearl River Bridge and Kikkoman Reduced Sodium Soy Sauce. It was enlightening as it taught me the perils of taste tests. Whichever soy sauce you used to develop the recipe will taste the best in that battery of recipes.

Amoy First Extract Light Soy Sauce is one I've been playing with for a few days now. It's only slightly saltier than the PRB. In comparing the flavors it has a more balanced nuanced complexity. However, it also contains sugar and caramel color. First extractions are normally used only in dips and not for cooking. I do think the nuances would be lost under heat and other flavors and best reserved for dipping. It costs more than the Pearl River Bridge as well.

See this update about Pearl River Bridge.

Soy sauce is inexpensive and it's worth conducting your own taste tests to discover what you like best. 

Dark Soy Sauce

I've not experimented as widely with dark soy. It's used almost purely in cooking and it's nuances aren't as clear used that way.

Amoy is the preference of Mai Leung though she differentiates her preferences among dark, double black and mushroom dark soys.

Koon Chun Double Black Soy is Eileen Yin Fei Lo's pick. 

Pearl River Bridge Mushroom Dark Soy is recommended by Mai Leung, Barbara Tropp,  Bruce Cost  I've mostly used PRB mushroom for my Dark Soy  but don't have a strong preference in this category. It gets a lot of votes from respected authors though.

Yuet Heung Yuen  Double Black for Mai Leung as she differentiates among the different types of dark soy

The preponderance of using the Mushroom variant for all Dark soy uses is one I practice too.

History of Soy Sauce is a worthwhile source for details about soy sauce.

Also my update on soy sauce testing, http://itsallabouttohappen.blogspot.com/2013/10/soy-sauce-choices-2013.html