Asian people and Vietnamese people partake in many foods that may be considered reviling to those who are unfamiliar with them. One of such foods is Trung Vit Lon -- fertilized duck eggs that are partway incubated. I call them half-hatched duck eggs. They are a delicacy in Vietnam, as well as a nutritious food that my mother says is a great restorative for women who've just delivered.
Contrary to current beliefs, Trung Vit Lon (pronounced "trung veet lone") are not traditional aphrodisiacs in Vietnam. They're a food for noshing (often with liquor, if you're a man) and perhaps, for weak and recovering women. Many Filipinos are crazy for Trung Vit Lon, which they call balut (pronounced "bahloot"). The eggs are a super popular Filipino street food, and there are Filipino aficionados who claimed that the eggs are a sex stimulant.
I have not had one since I was a kid in Vietnam but started thinking about Trung Vit Lon when prompted by Hoang, who emailed asking how the eggs are cooked and eaten. I remember eating them with my siblings, tapping on the egg shell with a spoon and then breaking the membrane underneath to sip at the flavorful liquid, which was broth like. Then we ate the solid stuff, which basically was the embryo. I don't recall beak, bones or feathers, but they can be in there, depending on the age of the egg. We didn't eat the hard white albumen. It was a kind of weird dare and that was it. It wasn't as positive of a food memory for me as my first bowl of Banh Mi.
When we got to the States, my mother said that it was hard to find a reliable source so we never had hot vit lon here. We gave it up, and I didn't miss them since there were lots of other great things to eat and obsess about. To digress, Mom loves to tell the story of a Vietnamese American Trung Vit Lon vendor who was making a delivery during the hot summer and his van broke down on the road. He was stuck waiting in the heat for a while. The eggs started hatching and soon, his had a load of ducklings instead of eggs to sell!
Seriously, for those who are curious, here's the lowdown on the eggs:
What are half-hatched eggs?
Half-hatched eggs are basically fertilized duck eggs (a.k.a. fetal duck eggs) that are 16 to 20 days in age. The older it is, the larger the chick and the more pronounced its feathers, bones, and beak. An embryo at 17 days has beak and feathers which are more developed at 20 days. Normally, after being fertilized, a chick hatches after 26 to 28 days of incubation. The taste depends on the breed of duck. Trung Vit Lon from Muscovy ducks (a leading breed in the U.S.) are considered among the best. You can half-hatch chicken eggs too but duck eggs are larger and more prized.
Who eats them?
Not just Vietnamese and Filipinos, but also Cambodians, Laotians, and Chinese. They're not as popular with Thais, Malays and Indonesians. Filipinos are the main connoisseurs of half-hatched duck eggs. For an in depth discussion, see this article on the significance of balut in Filipino culture.
Why eat them?
Look, I'm Vietnamese food lover but haven't had one in decades. But there are those who are extremely fond of them. Trung Vit Lon is full of nutrition (each has about 230 calories and offers 16 grams of protein and tons of B-carotene, calcium and other good stuff) so in circumstances where protein is in limited supply, it's quite a godsend. Eggs in many parts of the world are eaten more than poultry or fowl. A chicken or duck is better as an egg layer than roasted meat on your table. Beyond the nutritional aspects, there's the fun food factor, the memory of home, the nostalgia for foods of the past, the nosh to accompany beer or cognac.
The concept is one that's hard to swallow, but there are people out there for whom a half-hatched egg is the bomb. They may think it's weird that some people eat moldy, stinky cheese like Roquefort. I'm not saying to run out and eat one, but do understand that it's a well-liked food.
Where to buy the eggs:
They're mostly sold at Viet markets but how do you know their age? I'd buy them from the professionals to ensure freshness. For example, go to a farmer's market where there's a big Asian clientele. In Northern California, I've seen Trung Vit Lon sold at the Friday Oakland market and the Saturday Alemany (San Francisco) and Stockton markets. Look for an egg vendor, who may have signs in Tagalog, Chinese, and Vietnamese.
In Little Saigon enclaves, there may be a hot vit lon store, such as Trung Vit Lon Long An at 8942 Bolsa Avenue in Westminster, California.
For a party, you can even mail order them from Metzer Farm duck and goose hatchery in Gonzales, California!
How to cook half-hatched eggs:
The ones sold in the U.S. at markets are usually uncooked. Treat it like a humongous chicken egg and gently boil it for 20 to 30 minutes. It's enjoyed warmed, not cold.
Rau Giam.
How to eat the eggs:
Vietnamese people like to eat hot vit lon like you would a soft-boiled egg. Tap the broad end with a spoon, remove some of the shell. Break the membrane and sip the liquid. Then use the spoon to scoop up the solids. Add salt and pepper. Vietnamese people like to eat Trung Vit Lon with Rau Giam (Polygonum odoratum, Vietnamese coriander), a fresh herb that tastes cilantro but finishes with a bit of heat. The rau ram herb is suppose to offer heat to contrast with the cold of the egg, a yin-yang kind of thing. Others say that rau ram aids in digesting Trung Vit Lon.