Soaking ground coffee and water in a container overnight and filtering through a thick cotton pad produces a concentrate that can be added to hot or cold water to make individual cups of coffee. Cold brewing extracts the desirable flavor compounds (and the caffeine) but leaves behind many of the oils and fatty acids that give hot brewed coffee the familiar bite and make it difficult for some people to digest. When stored in the refrigerator, this concentrate has a shelf life of 14 days. Makes about 48 oz. of coffee concentrate per brew.