2 cups cold water – for diluting concentrate before serving
ice cubes – for serving
milk or plant milk – to taste (for serving, optional)
simple syrup or sugar – to taste (for serving, optional)
Instructions
Measure the coffee beans and grind them to a medium-coarse consistency, similar to coarse sea salt. Avoid grinding too fine, which can make the cold brew cloudy and overly bitter.
Place the ground coffee into a large jar, pitcher, or nonreactive container that can hold at least 5 cups of liquid, making sure it is clean and dry.
Pour 4 cups of cold water over the ground coffee in the container, stirring slowly with a spoon to ensure all the grounds are fully saturated and no dry pockets remain.
Cover the container with a lid or plastic wrap to protect it from odors and dust, leaving a small space for any gases to escape if the lid is very tight.
Place the covered container in the refrigerator or leave it at cool room temperature, and let the coffee steep undisturbed for 12 to 18 hours, until the liquid is dark and aromatic.
After steeping, set a fine-mesh strainer over a clean bowl or pitcher and line it with a paper coffee filter or a double layer of cheesecloth to catch fine sediment.
Slowly pour the cold-brew mixture through the lined strainer, letting the liquid drain through without pressing or squeezing the grounds, which can release extra bitterness.
Discard the used coffee grounds and the filter, then transfer the strained cold-brew concentrate to a clean jar or bottle and seal it tightly with a lid.
To serve, fill a glass with ice cubes, then combine 1 part cold-brew concentrate with about 0.5 part cold water from the reserved 2 cups, adjusting the ratio to taste for strength.
Add milk or plant milk to taste if desired, and sweeten with simple syrup or sugar, stirring until dissolved before tasting and adjusting.
Store any remaining cold-brew concentrate covered in the refrigerator for up to 1 week, shaking gently before each use and diluting with cold water, milk, or both just before serving.