Step 1

Place 1/4 cup coffee grounds into each jar, then top with water. Screw on the lids until just barely tightened; do not overtighten.

Step 2

Fill a large pot with enough water to cover the jars completely and place a sous vide immersion cooker into the water. Set temperature to 150 degrees F (65 degrees C) according to manufacturer's directions.

Step 3

Submerge mason jars into the water bath and set timer for 2 hours.

Step 4

Remove jars to a cooling rack and let cool until easily handled. Strain the mixture through a coffee filter to stop the steeping process. Pour over ice and serve, or return to rinsed-out jars and store in the refrigerator for up to 1 week.