Grind coffee beans to a medium coarse consistency.
Add water and ground coarse coffee beans to a wide-mouth mason jar or other glass storage container. Rest for 5 minutes and stir. Add vanilla bean (if using) and stir to combine.
Cover jar and refrigerate for 12-15 hours. Strain the coffee through a fine mesh sieve lined with a couple layers of cheesecloth over a large measuring cup or pitcher. Pour the strained cold brew concentrate back into a clean mason jar and store in the refrigerator.
To serve, pour the cold brew concentrate over ice, and your favorite milk or creamer. Cold brew concentrate will keep well in the refrigerator for up to 2 weeks, although I find that it has the best flavor within the first week. Enjoy!
