Condensed Milk Is What Separates Vietnamese Yogurt From The Rest

Because it can be used in everything from muesli to smoothies and tzatziki to key lime pie, yogurt is rightly a kitchen staple. The sweetened, fruit-filled versions make for a great snack, while plain Greek yogurt is indispensable for making a rich, tenderizing chicken marinade. According to Healthline, yogurt is packed with protein, vitamins, minerals, and probiotics (not counting the unhealthy store-bought kind), so there's not much downside to having it around. Because it's a fermented dairy product, yogurt by itself also happens to be quite tangy — well, most of it, anyway. It turns out that Vietnamese yogurt is made with sweet condensed milk, which not only balances the piquancy but also smoothes out the texture. 

In Vietnam, yogurt is called either Sữa Chua or Da Ua — the former translates to "sour milk," while the latter is a derivation of the French word yaourt. Given the fact that condensed milk is a pantry staple throughout Southeast Asia (perhaps most famously being a key component of the insanely sweet, strong, and delicious cà phê sữa đá, or Vietnamese coffee, considered the national drink), it should come as no surprise that it became the dairy of choice to be fermented into yogurt. (Or used to make delicious frozen Vietnamese coffee!)

Condensed milk had to be invented at some point. Unless you lived close to a lactating cow, you weren't going to have access to milk or milk products because of their perishability. Condensed milk is made from regular cow's milk (with 60% of its water removed), sugar (added as a preservative), and a heating process that further thickens it. In 1864, Gail Borden opened a massive milk condensery in New York, processing 20,000 gallons of milk a day. This nutritious, stable product was carried in the field by Civil War soldiers.

By the same token, a war brought condensed milk to Southeast Asia, too. Canned goods, including condensed milk, were introduced into what was known as French Indochina (an area now including Vietnam, Cambodia, and Laos) in the 19th century by French colonizers. In Vietnam, condensed milk factories were collectivized after the American war ended in 1975. One of their most beloved products is called Sữa Ông Thọ, or, literally, Mr. Longevity milk. The old timers stir it into their coffee, while home cooks use it to make yogurt.

While it might seem tricky, making Vietnamese yogurt at home is no big deal at all — especially if you have an Instant Pot or something similar. All you need is whole milk, condensed milk, and yogurt. (That's not a typo: a yogurt containing live yeast cultures is the exact "starter" needed for this operation, just like when making sourdough bread.) Oh, and you'll also need one other ingredient: time. If everything is done correctly, your batch of homemade Vietnamese yogurt should be ready to refrigerate in eight to 10 hours.

You can eat Vietnamese yogurt plain, combine it with fruit and freeze it into popsicles, or use it in the aforementioned chicken marinade. Because of its balance, it serves equally well in savory as well as sweet applications. Think of Vietnamese yogurt as your gateway into the wonderful world of home fermentation.