Over the past few years cold brew has emerged as one of the most popular ways to drink cold coffee, and rightly so as cold brew offers a unique flavor profile that highlights the bass-ier tones of a coffee, shining a light on chocolate and caramel flavors alongside an emphasized body and moderated acidity. However for coffee drinkers looking for a brighter, more aromatic profile a method called “flash brew” is a great option, and one that is easy to make at home.
Flash brewing essentially involves brewing a strong cup of hot coffee and diluting it with ice, which rapidly drops the temperature (flash chills) and brings the strength into balance. This kind of approach isn’t necessarily new, restaurants and diners have been icing old pots of hot coffee for tomorrow’s iced forever, but the key differentiator in a flash brew recipe is the built in dilution, ensuring the final result is not only cold but delicious. We typically recommend starting with a 1:16 brew ratio for hot filter coffee as this produces a sweet and balanced cup, but diluting this further with ice would drop the strength too low, and the sensations of sweetness, complexity and freshness would all be lost. In order to retain as much of the origin flavor as possible, our flash brew recipe calls for a significantly stronger brew ratio in tandem with a finer grind and extended bloom to achieve a proper extraction and high strength so the dilution won’t negatively impact the final cup. The finished brew is made with a ratio between 1:14 and 1:15, but only 60% of our water weight is actually used to brew the coffee with the remaining 40% coming from the ice added at the end. This means we’re brewing below a 1:10 ratio prior to dilution!
This recipe can be scaled up to produce larger batches, though we strongly recommend making it fresh the day you plan on enjoying it, but there’s a bit less wiggle room in scaling down. Since only 60% of the water weight is being used in the brew, contact time (how long the water and grounds are mixed together in the brewing process) is at a bit of a premium. If the brew becomes too small, you’ll need to use too fine of a grind which can contribute muddy and bitter flavors.
Finally, while our recipe is designed to use the Kalita Wave, flash brewed iced coffee can be made with a variety of methods, including other pour over devices like the Chemex, an automatic drip machine or even immersion methods like the French Press or Aeropress by replacing roughly 40% of the brew water with ice and adjusting the dose and grind. Happy brewing!
Flash Brewed Kalita Wave
- Kalita Wave 185 brewer, filter & decanter
- 35g of coffee, ground finely
- 300g of water, 208° F
- 200g ice
- Weigh 35g of coffee and grind on a fine setting similar to table salt. Set up the Kalita Wave, filter, and vessel on the scale. Heat water in the kettle to 208° Fahrenheit.
- Gently pour hot water into the center of the empty filter. Continue pouring in a spiral outwards to wet the entire filter. Be careful not to pour too hard as the filter can collapse. Empty the water from the vessel, place back onto the scale, and tare to zero.
- Add the coffee to the Kalita Wave with the vessel on the scale, ensuring that you add 35g of ground coffee, and tare to zero.
- Start the timer and add 70g of water to the bed of coffee quickly, in about 5 seconds. Stir the bloom with a spoon a few times ensuring all of the grounds have been saturated and mixed. Let the coffee bloom for one minute.
- When the timer reads 1:00, start pouring in the center and spiral out in concentric circles with a strong flow. It’s okay to pour onto the filter walls if grounds are clinging to the paper. Continue pouring until the scale reads 150. This should take roughly 10 seconds. Let the slurry drain for roughly 10 seconds, or by about half an inch.
- When the timer reads 1:20 quickly add another 50g of water to raise the level again and bring the total brew weight to 200. This should take roughly 10 seconds. Let the slurry drain for roughly 10 seconds, or by about half an inch.
- When the timer reads 1:40 quickly add another 50g of water to raise the level again and bring the total brew weight to 250. This should take roughly 10 seconds. Let the slurry drain for roughly 10 seconds, or by about half an inch.
- When the timer reads 2:00 quickly add the final 50g of water to raise the level again and bring the total brew weight to 300. This should take roughly 10 seconds. Let the slurry drain completely. This should take between 45 seconds and 1 minute.
- When the slurry has drained completely, remove the brewer from the decanter and tare the scale so that it reads zero. Add 200g of ice to the decanter and stir to incorporate.
- Flash brewed iced coffee is ready to drink as is or over fresh ice. Enjoy!