The Filipino street food consisting of a fertilized duck egg is balut.
Balut is a developing, fertilized duck egg that is incubated for roughly two to three weeks, then boiled or steamed and eaten directly from its shell. In the Philippines, vendors commonly incubate eggs for about 14 to 18 days, with around 17 days often considered a preferred stage.
The finished egg contains broth, yolk and a partially developed duck embryo. Diners typically crack the shell, sip the flavorful liquid, then season the contents with salt, vinegar or a spicy mixture. The embryo’s texture and appearance change according to incubation time, so people have different preferences about when it is cooked.
Balut is especially associated with the Philippines, but related preparations are also eaten in Vietnam and Cambodia. It is sometimes confused with penoy, a duck egg incubated without a successfully developed embryo. Isaw, taho and kwek kwek are Filipino street foods, but none is a fertilized egg.