Vietnamese iced coffee (café sua da) is brewed strong with a drip apparatus and mixed with condensed milk. "Using condensed milk is the authentic way to prepare Viet iced coffee," says MVNYC. "Vietnam, like many other tropical locations, uses condensed milk because it does not spoil without refrigeration like regular milk does." Condensed milk is not the only unusual additive; Vietnamese coffee is often blended with chicory prior to brewing. (Café du Monde is a brand commonly available in the United States.) But most Vietnamese coffee in Vietnam, says paulj, is not made with chicory. Instead, it's a blend of the more expensive Arabica beans and cheaper, more harshly flavored Robusta beans. "By itself it is too harsh for American palates that have been trained to like pure Arabica," says paulj. "But it works well with sweetened condensed milk, which has a strong tempering effect."
Thai iced coffee is also made with condensed milk, and it's also often brewed from a blend of ingredients, not just coffee beans. Classic ingredients for the blend include corn and sesame, but in the United States sometimes the additives get left out: "[O]ften I go to places where it is just strong coffee with condensed milk," says Jemon.