To the uninitiated Westerner, China is like a century egg. From the outside, it appears like a Western boiled egg. But once you go past the shell, the similarities end. Whereas a Western boiled egg is brightly-colored and solid, with clearly demarcated lines between white and yellow, a century egg is dark and complex, with a sharp, acrid smell that requires a few tries before appealing to the Western palate. But in order to truly understand China and Chinese culture, the Westerner must, both figuratively and literally, learn to love the century egg.
Called century egg, 100-year-egg, and even 1,000-year-egg or millennium egg in English, the Chinese call this delicacy 皮蛋 (pídàn, meaning literally skin egg or leather egg for its appearance). A century egg is a chicken or duck egg (duck eggs are better in my opinion) that is preserved by changing the chemical composition of the protein and fat.
A raw egg is buried in a pasty mixture of salt, clay, ash, quicklime, and rice grain hulls for a period of time, the more finely-aged and prized eggs generally being buried longer, up to five weeks or even a few months. This process, at least 600 years old, is essentially a pickling process. The quicklime and ash raise the pH of the eggs, causing them to become less acidic, and much more basic. This in turn breaks down the protein and fat molecules, changing their appearance, texture, and flavor. The process is also a potent bactericide, and so century eggs are preserved from deterioration and can be stored through a winter.
When I say that the process changes the flavor, I mean it really changes the flavor. Century eggs have an odor and flavor that are acidic, acrid, sharp, a bit bitter and sour, and very complex. They are China’s answer to aged European cheese. The flavor can be a bit off-putting and strong — even unbearably so — to the uninitiated Western palate, but a really high-quality century egg has a rich, tangy complexity that is delicious and alluring. And the odor is more acrid than the flavor, like various aged cheeses.
I bought some century eggs at the market, and made 粥 (zhōu, a Cantonese rice porridge) with them. This classic Cantonese dish is basically rice that is cooked until it is soft like a porridge, to which ground pork, century eggs, and a bit of salt are added. There are many other variations of zhōu as well. The warm, salty, mild softness of the rice offset the harsh, pungent flavor of the century eggs, and the pork acted as a sort of catalyst to join the two.
If you have never tried a real century egg, then you should, especially if you love international cuisine. Perhaps repulsive at first, like some aspects of Chinese culture, you must first acclimate yourself to century eggs, piece-by-piece, bit-by-bit, continuing to try until you finally understand why they are prized.