Measure 16 oz of water and bring to a boil on your stove top or in a hot water kettle.
Measure out 4oz of coarse ground coffee on a scale. Pour ground coffee into the bottom of a 32 oz or greater glass container. Or to eliminate final step use a large fine mesh cheese cloth or other cloth filter to create a 'tea bag' for the coffee. If you go this route be sure to keep the cloth very loosely fitting around the coffee. If it is too tight around the coffee the water will not be able to contact the coffee properly.
Once your water has begun to boil, remove from heat and pour over coffee grounds inside your container. Pour water in 3 portions stirring between each. Steep for ~30 - 45 minutes.
Measure 16 oz. of cold water and pour into your steeping coffee until nearly full leaving room to stir one last time. Seal container with a tight fitting lid or plastic wrap and move to refrigerator.
If you did not use cheese cloth or filter to brew, open your container after 12 - 24 hours and strain. Do not stir or shake before straining as the coffee will settle to the bottom and you may be able to simply pour your cold brew off the top into its final storage container. Serve over ice or with milk.
If you did use a filter, open your container and remove filter with the coffee grounds and drain without squeezing. Coffee is now ready to serve.