A cup of ca phe trung, or Vietnamese egg coffee, is topped with a dense, custardlike foam layered over strong, dark coffee. The foam is made by whipping egg yolks with sugar. (Chrissy Yates/Stars and Stripes) Last July, Khanh Linh Vu-Holwegner posted an invitation in a local Facebook group to the grand opening of Fee & Tee, a Vietnamese-style coffee shop in Kaiserslautern. People most commonly associate Vietnam with strong, sweet iced coffee made with condensed milk, known as ca phe sua da.