Recently a finely packaged gift box edition of Dingxin Soy Sauce has gone on sale, making superb holiday presents among the people of southern Taiwan. (Jimmy Lin)

The Taiwanese idiom "a black bottle filled with soy sauce" is an expression of surprise at something unclear or unfathomable. You may also feel a sense of surprise about the soy sauce made way down south at Pingtung Prison.

Come again? Well, this so happens to be where southern Taiwan's well-known Dingxin Soy Sauce is made. The selling point of this brand, dating back to 1960, is that it's pure, hand-made soy sauce fermented according to age-old methods, made with wholesome ingredients, and boasting a mellow, not overpoweringly salty flavor, fully conforming to modern folk's health needs. Recently, its annual output has surpassed the NT$24 million mark.

Behind this broad-based consumer popularity is the laborious work of many pairs of brawny, tattooed arms. The repute of this "gangster" soy sauce has persisted for years, and is the pride of Taiwan's prison administration.

"Say, Missy, you're doing a soy sauce interview over yonder at Pingtung Prison, eh? I'm no shill for them, but I gotta say their soy sauce is damn good! And a real deal, at under 50 bucks a bottle. We've been buying their sauce for 20 years, and now the other brands just ain't the same to me."

The driver of the cab I hailed randomly from downtown Pingtung sounded like someone giving a testimonial on a shopping channel as we made our way to Zhutian Township, home of Pingtung Prison. The cabbie, a Kaohsiung resident, chattered incessantly about the different flavors of soy sauce available at Pingtung Prison. That such innocuous conversation could evoke a response like this is testament to the popularity of this "gangster" soy sauce.