Ca Phe Trung, or egg coffee, is a unique and delicious beverage that is a must-try in Halong. This Vietnamese specialty is made by whisking egg yolks with condensed milk and coffee, creating a rich and creamy concoction. The mixture is then poured over a cup of hot black coffee, resulting in a sweet and velvety drink. Ca Phe Trung is a popular choice for coffee lovers in Halong, offering a unique twist on the traditional cup of joe.