Flash brewing is a method in which you brew hot coffee directly over ice, instead of chilling hot coffee after brewing. This brew results in an aromatic and crisp cup, thanks to the effects of ‘shocking’ the coffee with ice as it flows through the dripper. These wonderful flavors are brought to us by the science of coffee extraction.
Flash brewing changes extraction in a few important ways:
Hot Water = Full Extraction
You still use hot water (around 195–205°F), which extracts flavor compounds efficiently; especially acids, sugars, and aromatics that cold water can't easily reach.
Rapid Chilling = Aroma & Acidity Preservation
Chilling immediately locks in the volatile aromatic compounds that would normally be lost during slow cooling. This helps preserve floral, fruity, or bright notes that define high-quality coffees.
Dilution by Design
Since part of your total water is in the form of ice, your hot brew is more concentrated, then diluted by the melting ice. This avoids over-extraction.
Shorter Brew Time
Flash brews are faster than cold brews (which steep for 18–24 hours), but you still get a smooth and vibrant cup without the muted, sometimes flat profile of long steeping.
Flash Brew Recipe (V60)
What you’ll need
Hario V60 Brewer and filter
30g coffee
320g water
Carafe/brewing vessel
1. Begin by rinsing your filter to remove any paper taste.
2. Fill the carafe with 120-130 grams of ice.
3. Grind the 30g of coffee to table-salt fineness.
4. First pour: 90g of water heated to 205F, allow to bloom for 1 minute. Stir the slurry with a spoon to ensure all the grounds are fully saturated.
5. At 1 minute, slowly pour up to 200g water.
6. At 1:40, slowly pour up to 320g water.
7. Allow the coffee to drop completely until the brew-bed is dry. Add ice to the carafe, give it a swirl, and pour into your favorite cup for pure enjoyment.