Drink egg coffee where it was invented, at Cafe Giang
The 1946 original, down an alley
A narrow, three-storey cafe reached down an alley off Nguyen Huu Huan, serving a small glass of strong coffee under a thick, sweet, whisked egg-yolk custard. It is set in a bowl of hot water so the custard does not stiffen before you finish.
Why it's unique
Egg coffee was invented in this city in 1946 by Nguyen Van Giang, a bartender at the Metropole hotel who whisked egg yolk into coffee because a wartime dairy shortage had taken milk off the shelves. The drink was popular enough that he left and opened his own cafe on the strength of it.
That cafe is still there, still run by his family, and this is the cup that every egg coffee served anywhere else is a copy of. You can drink the same drink in a hundred places now. There is one place where somebody thought of it.
Before you go
The entrance looks like the corridor into somebody's flat, and most people walk past it. Go down the alley; the cafe opens out at the back and continues upstairs, where the seating is.
Order it hot. The iced version is on the menu and loses the whole point, which is the temperature contrast between the custard and the coffee underneath. Stir once from the bottom to break the layer, then leave it alone. This is a drink Hanoians take slowly, closer to a dessert than a caffeine stop, so do not order it to take away.