The great Filipino delicacy is balut - a boiled fertilised duck egg which non-Filipinos are pretty squeamish about. It's not like a normal egg since the shell contains a partially developed duckling complete with recognisable features. This famous and very nutritious snack is provided by pedlars on many street corners throughout the Phillipines.

Only the strong-shelled and apparently fertile eggs are selected for balut-making and this is done by "candling". Making balut is a complicated business. The selected eggs are first incubated between bags of toasted palay (whole rice grains with husk) or ipa (rice husk) to stimulate the body temperature of the mother duck. They are then layered with sako (burlap bags) to serve as insulators. Complete development or hatching takes place within 28 days of incubation. Those which are fertile but have failed to develop are boiled and sold as penoy. Their appearance is similar to a hard-cooked duck egg. The balut are those incubated up to the 18th day and which contain a healthy living embryo. Like penoy, they are boiled and eaten as a snack food. In fact, these two are sold together just as one is given a choice of coffee or tea. Filipinos are used to the calls of young street vendors peddling their wares: "Balut...penoy!"

Balut and penoy are traditionally considered aphrodisiacs. While it is true that they have high nutrient values there is no hard evidence to prove this. Aphrodisiacs or not, balut and penoy are enjoyed by millions of Filipinos. For the non-Filipino, an adventurous spirit, a desire to explore the unknown and the ability to be open-minded are essential to the enjoyment of balut. A combination of saltiness and tartness, softness and crunchiness, a sensation of sweetness, the degree of resistance to the bite, the viscosity and stickiness are the rewards.

Today, the humble balut has been slicked over, enveloped in puff pastry, oven-baked, perfumed with various spices and undergone so many transformations that it is a minor miracle that the poor thing still manages to remember that it really is nothing more than a duck's egg.