Coarsely grind coffee. I use a "10" setting on my Fellow Ode or "35" on Baratza Virtuoso. Because of the long brew time, you want to keep your coffee ground coarse to avoid over extraction.
Add 40 grams of ground coffee to the bottom of the mason jar.
Add 320 grams of water (ideally filtered) to the mason jar.
Gently stir coffee and water to make sure all of the coffee is saturated with water. You do not want any coffee grounds sitting on top of the water.
Twist a lid lightly onto the jar and set on the counter to brew. Brew time can be anywhere from 12-24 hours, though I have found 18 hours to be a perfect amount of time.
After brewing, strain the brewed coffee from the mason jar into a glass or second jar. You can use a strainer, cheese cloth or even a coffee filter to strain the coffee.
Add ice, milk or water to taste. The final cold brew in this recipe is a bit stronger, so you have the flexibility to dilute as necessary. Enjoy the cold brew right away or store in the fridge for up to a week.