I was in a banh mi shop today and ordered a hot Vietnamese coffee. The shopkeeper put some refrigerated concentrate and condensed milk in the cup, and then added hot water. Is this a standard method for selling large volumes of Vietnamese coffee? And if so, how is the concentrate made? Is it a cold brew method like this, or do they do it some other way?
NB: I'm in the US, if it matters.
Apparently they used some sort of a pour over method, I'm not very sure about it though because they wouldn't expose their trade secrets to me ;).
What I am sure is it is common practice for the Vietnamese to sell from concentrate, because they brew a batch in one go then refrigerate it until it is used, not unlike cold brews. If you're a fan of espresso, you can drink the concentrate straight up.
Source: A Vietnamese coffee seller during a trip
In Vietnam the standard method of selling large amounts of coffee is the same as the small amount: every single cup will always be served with its own metal filter (phin), and after the coffee has dripped through the customer places the filter over the lid. In case of milk coffee, the condensed milk is at the bottom of the cup.
If the customer wants iced coffee they will pour the coffee over the ice themselves.
A concentrate is never used if time allows it. However in some takeaway stalls they use the Trung Nguyên bottled "fresh" coffee for iced coffee - this is never diluted with water, however. No one would ever accept it for warm coffee either.
