What Is A Century Egg And How Should You Eat It?

You might know this distinctive ingredient as a "century egg" or "thousand-year-old egg." You might even know it by its Chinese name — "pidan" (pronounced pee-tan). No matter how you refer to it, though, you're not likely to forget a century egg if you've been served one, simply because it neither looks nor tastes like any egg you might have consumed before.

Contrary to popular folklore, century eggs don't need a hundred years — never mind a thousand — to end up looking, tasting, and smelling the way they do. Food52 says the process of turning a run-of-the-mill duck, chicken, or quail egg into a century egg takes just three months of sitting in quicklime, salt, and ash under a blanket of rice chaff to become one of the best loved ingredients in Asian cuisine. Once they're ready to go, a peeled century egg will reveal a former egg white gone dark and gelatinous, while what was once the egg yolk is now a dark green with a squishy consistency, similar to a half hard-boiled egg. The eggs can also have a sulfuric smell, which is likely why they (undeservedly?) occupy a place in the Disgusting Food Museum.

Folklore around century eggs

Century eggs have been around a while. Travel Food Atlas says they were probably discovered during the Ming Dynasty, about 600 years ago, but legends vary as to how they were first discovered. One food origin story says they were discovered by a man who, while he was building a new home, had discovered a cache of duck eggs lying in lime for some time. Another story has them as the offering of a man who had left them in the garden of a woman he had been courting, but the eggs were not discovered until weeks later.

What is certain is that the practice of buying eggs in ash or lime was used to ensure the eggs' longevity at a time when preservation methods were limited. MasterClass says that people covered eggs in a mixture made with wood ash, salt, and calcium oxide mixed in a strong black tea, then wrapped them in rice husks while chemistry did its job and cured the eggs. While duck eggs are normally used to make century eggs, the delicacy can also be made with quail and chicken eggs. And while they might be an acquired taste, century eggs are a lively addition to any hot or cold dish they are used in.

Century egg can be served cold, mixed into a salad

Because century eggs can be consumed after their hibernation, a good number of dishes that century eggs can be found in are cold. The delicacy is traditionally enjoyed quartered and served with pickled ginger to cut through the rich flavor of the egg. Per SCMP, they are also often served up as the co-star of a chilled tofu and leek dish with a dressing made with soy sauce, ginger, garlic, sesame oil, and Japanese mirin.

But century eggs can be served hot, too. One classic way to enjoy this versatile egg is as part of the Cantonese rice porridge known as congee, when it is diced and served as a condiment, along with pork floss. Century egg can also be cooked up into a broth with salted eggs and regular eggs, to which spinach is added for a memorable meal that's suitable for vegetarians who don't shy away from eggs.

Century eggs can even be baked into a flaky pastry dessert — which challenges the trope that century eggs are always part of a savory dish. But one truly memorable way to enjoy century eggs is when they are quartered and fried up kung-pao style with Sichuan peppercorns, chiles, and garlic, then tossed in a soy sauce-based mix, as this YouTube video demonstrates.

Century eggs can be made at home

While it might sound challenging to make your own century eggs at home, it can be done. MasterClass lists out a recipe that involves quail eggs, and which calls for black tea, kosher salt, food-grade lye, and food-grade zinc. It warns that you must be wearing protective gloves for this procedure, and that you are in a well-ventilated room. All told, the eggs can take just over a month to prepare, from start to finish.

While it is so much easier to pop to the Asian supermarket to buy century eggs, there could be a good reason to make them at home. The Disgusting Food Museum warns that there were incidents in 2013 of century egg producers in China as having used toxic chemicals and heavy metals. Today, century eggs produced in China need to met certain standards: They cannot be found with any "foreign materials" like dirt, feathers, hair, or insects; they should have a standardized weight of between 100 to 120 grams; and their shells cannot have any cracks or holes.