Here's a brief recipe for flash-brewed iced coffee.

RECIPE

Brewer Used: Hario Switch or Clever

Brew Ratio: 1 to 14.5

• 21.5 grams of ground coffee
• 150 grams hot water
• 150 grams ice

Steps:

1. Set up the brewer with a cleaned filter and the ground coffee over a carafe filled with 150 grams of ice.
2. With the valve closed, start a timer and add 150 grams of hot water quickly and evenly to the coffee grind, then wait.
3. After 1 minute of total elapsed time, gently stir the coffee briefly to break the crust, then wait.
4. After 3 minutes and 30 seconds total elapsed time, drain coffee onto 150 grams of ice.
5. Mix until the brewed coffee until the ice is fully melted.
6. Pour into serving cup and add more ice to your liking.

We used the Hario Switch, but you can easily use the Clever. These are full-immersion type brewers where the water and ground coffee stay in contact for the full brew time, and a mechanism allows the water to drain through a valve at the bottom of the cone. If you don't have this kind of brewer, you can substitute with any other kind of filter brewer. 

Alternate Steps:

1. Set up the brewer with a cleaned filter over a carafe filled with 150 grams of ice.
2. In a separate, heat-safe vessel, add the ground coffee and pour 150 grams of hot water quickly and evenly to the coffee, then wait.
3. After 1 minute of total elapsed time, gently stir the coffee briefly to break the crust, then wait.
4. After 3 minutes and 30 seconds total elapsed time, drain hot coffee and grinds through the filter cone onto 150 grams of ice.
5. Mix until the brewed coffee until the ice is fully melted.
6. Pour into serving cup and add more ice to your liking.

MORE INFO

Flash-brewed iced coffee is simply brewing a pour-over coffee with hot water over ice to instantly chill it down to be enjoyed cold. This is different from cold-brewed iced coffee which is usually brewed at room-temperature or cooler, usually for a minimum of 6 hours, but possibly up to 24 hours depending on the recipe. The different brewing methods result in different flavor profiles. Cold-brewed coffee has a "smoother" flavor, while flash-brewed iced coffee may be more "lively." Cold-brewing can be handy for preparing larger batches, while flash-brewing is good for a spontaneous and refreshing cup for yourself.