During World War II, Nguyen Gian faced a problem: a milk shortage. He was working in a hotel in Hanoi, Vietnam, and his solution was to mix whipped eggs into the coffee. This classic case of constraints spurring creativity is widely credited as the moment that cà phê trứng, or Vietnamese egg coffee, was invented. Over the years, Gian, along with other residents of Hanoi, a highly caffeinated city, developed egg coffee into a drink you want even when plenty of milk is on the table. It combines the strength…
