Grind coffee to a coarse grind. Add to a clean jar or pitcher that can hold at least 2 quarts.
Add cold water to the jar. Stir to thoroughly moisten the coffee grounds. Cover jar and place in the refrigerator for 12-24 hours.
Line a fine-mesh strainer with cheesecloth and set it over a large measuring cup. Slowly pour the coffee through the strainer. Allow the coffee concentrate to slowly filter. DO not stir or press the grounds to make it go faster.
Transfer coffee concentrate to a clean jar or pitcher. Keep in the refrigerator for up to 2 weeks.
When ready to make a cup of cold brew, add equal parts cold brew concentrate and cold water over ice.
Notes
Recipe can easily be scaled up or down. Use the ratio 1 ounce of coffee beans to 1 cup of water.