By Tao Jun, Nguyen Xuan

HANOI, July 1 (Xinhua) -- "Coffee and...egg, together?" Yes, it may sound strange but it certainly forms a must-try drink in Vietnamese capital city of Hanoi nowadays.

On Nguyen Huu Huan, one of the endlessly busy streets in Hanoi's Old Quarter, an almost hidden cafe lies in a narrow alley where people can find the most authentic version for "ca phe trung", or Vietnamese egg-coffee mix, in town.

The 70-year-old-plus "Cafe Giang" was packed on both floors by locals and tourists on Tuesday afternoon. They sat around the old square wooden tables, either lively chatting with companions, or silently sipping a cup of coffee, and surely, with egg.

Nearby the stairs to the second floor places a modest, open-plan kitchen where Nguyen Tri Hoa, owner of Cafe Giang, is whipping up egg yolks with sugar and condensed milk, and other parts of the recipe.

The mix is then boiled. Next comes coffee, it is quickly poured into the beaten eggs, forming a beautiful and aromatic foam. A teaspoon is provided to drinkers for them to eat the foam before drinking the coffee at the bottom.

Egg coffee is served in hot and cold versions. The former comes resting in a small dish of hot water to maintain its temperature. When the strong coffee taste at the bottom of the cup seeps through the egg -- the yellow layer on top -- it becomes richer, thick and sweet.

"It's my favorite choice all year round. But you'd better to take it in autumn and winter to taste the best of it," Quan, a 25-year-old Hanoian told Xinhua.

As a loyal customer, the young man usually comes here with his friends. Though plenty of coffee shops in Hanoi now serve the dish, Quan believes Giang's distinctive rich and foamy coffee deserves the greatest reputation in town.

The cold option, introduced in the 2000s, is served as a yellow concoction in a small glass. Laden with ice, it is consumed with a spoon and tastes almost like a coffee-flavored ice cream -- more like a dessert than coffee.

To foreigners, a "wow" reaction is not rare when they encounter the unique drink.

"It's the first time I've tried, with egg, it's a little bit strange," said Prisca, 26 from France, with an excited face.

"Nice," she concluded satisfactorily, while her companion, the 27-year-old Vidian from Guadeloupe, a French overseas region, an island group in the southern Caribbean Sea, came up with the same answer, "It's a good experience."

According to Nguyen Tri Hoa, his father Nguyen Van Giang created the drink in 1946 while working as a bar tender at Sofitel Legend Metropole Hotel in Hanoi. A milk shortage then forced Giang to cast around for alternatives and he found eggs. That is how Vietnamese egg coffee was born.

Hoa, the youngest son of the family, is also the first one to follow his father's path. Time passes by, he has enrichened the old menu with several new creations.

"I started to make cocoa eggs and white bean eggs in 1999. And then in 2010, after welcoming so many foreign customers and also travelling a lot, I realized that rum and beer can be great complements to egg," Hoa recalled.

While Hoa runs the family's premise on Nguyen Huu Huan Street, his older sister and brother, respectively set up two other egg coffee shops on Dinh Tien Hoang Street, Cafe Dinh and on Yen Phu Street, Cafe Giang Yen Phu.

Cafe Dinh, the 20-square-meter place with a modest balcony, is on the second floor of a bag shop. Though slightly hidden and hard to locate, it offers a nice view over Hanoi's iconic Hoan Guom Lake. With music, flowers, unique coffee and sunflower seeds, it is a place where many locals chat, text, smoke, play games, or read news as the coffee drips timelessly through the filters.

Cafe Giang Yen Phu, not as crowded as its two siblings, lies outside the Old Quarter. Gathering on blue and red plastic chairs, people chill and blend right in with their egg-coffee mix, which may taste a bit softer but deeper than at Cafe Dinh.

"When I think about Hanoi, egg coffee is one of the first images come out, with other things like Hoan Kiem Lake, the Old Quarter or the Literature Temple. It is not just a drink, it is a symbol, a culture of the capital," said the Hanoian Quan.