The Flash

April 18, 2017


The warm weather is upon us and with it iced coffee season! It’s no secret that we love cold brew here at Corvus; we have five different kinds in bottles alone not including the many Kyoto cold brews you can try at our DTC location. But those all take hours to make, and if I’m outside by the pool craving iced coffee, I don’t always want to wait until sundown to drink it! In that case, I’ll use a method we refer to simply as “flash brew” in which we use hot water to brew coffee directly onto ice. It makes a really sweet cup of iced coffee in mere minutes rather than waiting hours for immersion-style cold brew.


I enjoy using the chemex for this for a couple of reasons. For one, it’s big enough to hold a few cups so I don’t have to keep brewing non-stop, and it’s also its own decanter which is pretty handy, too.

Here’s where I get hung up when it comes to recipe creation for flash brew. When making hot coffee, the cup is entirely made up of water that passes through the bed of grounds. In the case of flash brew, some of the the water is from melted ice that was not used to brew the coffee. But it still affects the final strength which, by the way, is constantly changing as the ice melts. I’m a bit of a numbers nerd with my recipes, so this melting ice concept had me chasing my tail.

I was using our Boloya from Ethiopia which is always delicious, so how hard could it be? I tried several things: Increasing the ground coffee dose by 50%, 100%, coarse grind, fine grind, I even tried brewing the coffee at a super strong concentration and adding the ice afterward. Nothing seemed to be working, and that was when I learned my lesson. I was over-thinking it. So, I finally tried something simple: Take half of the brew water away and replace it with ice in the decanter. Using half of the normal amount of water to brew coffee would make me expect an under-extracted sour tasting cup that is too strong. But what resulted was sweet, bright, and balanced. 

I always say this in the coffee classes I teach: The numbers don’t mean anything if it doesn’t taste good. And just when you think you know a thing, coffee will humble you. I guess that’s just the magic of it all.


Here’s the exact recipe I used:

21 grams of Ethiopia Boloya ground medium

160 grams ice in the bottom of the chemex

176 grams of boiling water to brew


If you don’t have a chemex, use my trainer code “flashbrew" for 10% off online or in store!

limited to 20 customers