Vietnamese-Style Cold Brew

In a country as hot as Vietnam, iced coffee is part of daily life. For a long time, the familiar way to make it was to brew a very strong hot phin and pour it over ice. In recent years, many cafés have added small glass bottles to their chillers labelled "cold brew" — coffee that isn't brewed hot at all, but steeped cold overnight.

This article explains what cold brew is, why it tastes different from traditional iced coffee, and how Vietnamese drinkers have adapted it to their own taste.

What is cold brew?

Cold brew is coarsely ground coffee steeped in cold or room-temperature water for about 12–24 hours, then filtered. The result is a strong concentrate that you dilute with water, milk or ice when you drink it.

Without heat, extraction is slower and "gentler". Some compounds responsible for sharp acidity and harsh bitterness dissolve readily in hot water but much less in cold water. So cold brew is usually described as:

• Smooth and round, with little sharpness.
• Naturally sweet on the finish, with clearer chocolate and caramel notes.
• Less aromatic than hot coffee, because many aroma compounds need heat to be released.

How is it different from traditional iced coffee?

The two can use the same beans but give very different experiences. Hot-brewed iced coffee has the familiar "kick" many Vietnamese drinkers love. Cold brew is gentler, suiting those who like their coffee black without much sugar.

Making cold brew at home

No special equipment needed — a glass jar with a lid and a filter are enough.

Ingredients (for about 1 litre of concentrate):

• 125–200 g of coarsely ground coffee (like sea salt).
• 1 litre of filtered water, cold or at room temperature.
• A ratio of about 1:5 – 1:8 for a strong concentrate.

Steps:

1. Put the coffee in the jar, add the water and stir gently so all the grounds are wet.
2. Cover and steep for 12–24 hours. At room temperature it is faster (about 12–16 hours); in the fridge, allow longer (about 18–24 hours).
3. Filter twice: first through a sieve or cloth bag to remove the grounds, then through paper for a clean cup.
4. Store the concentrate in the fridge in a clean, sealed bottle, and drink it within a few days.
5. To serve, mix the concentrate with water, milk or ice at about 1:1 to 1:2, depending on how strong you like it.

A safety note: cold brew is never boiled, so keep your jar, sieve and hands very clean. If it smells odd or tastes unusually sour, don't drink it.

Vietnamese ways to drink cold brew

Once cold brew reached Vietnamese cafés, it was quickly "Vietnamised":

• Cold brew with condensed milk: concentrate stirred with condensed milk and poured over ice — the spirit of iced milk coffee, but smoother.
• Cold brew with orange or kumquat: concentrate mixed with orange juice or a few slices of kumquat for a bright, refreshing drink on hot days.
• Cold brew with coconut: concentrate with coconut milk and ice, creamy yet light.
• Black Robusta cold brew: cold-steeped Robusta keeps its full body and dark chocolate notes, but is less harsh than when brewed hot.

Many cafés also sell bottled cold brew concentrate to take away, so customers can mix it at home or bring it to work.

Choosing beans and roast

Cold brew softens acidity, so medium to dark roasts usually give an easy-drinking, sweet, round result. Vietnamese Robusta is a natural fit: its full body keeps the coffee's character even with lots of milk or ice. Medium-roast Arabica makes a lighter cold brew with a hint of fruit.

A slow brew for hot days

Cold brew takes patience: steep it overnight for coffee that lasts the week. In that sense, it is quite close to the unhurried spirit of the phin. To compare it with hot methods, see The Phin Filter — Icon of Vietnamese Coffee and Vietnamese-Style Pour-Over, or go back to the most familiar drink of all — Vietnamese Iced Milk Coffee.