You can predict it each year: as the mercury climbs, legions abandon their thermally insulated mugs and scramble for cold coffee. Whether you're an old hand at cold brew, or new to the slow, all-night magic of preparing cool coffee for hot days, it's time to get out the strainer and get your chill on.
Cold brew methods are exalted for the low-acid coffee produced, and as such are ideal for brewing not only a refreshing cup but one that's mellow on your stomach. The overnight process of steeping coffee in water at room temperature yields a gentle-on-the-digestion concentrate, that you can use again and again—the only time you're allowed to make coffee just once, but keep drinking the rewards over and over. The process is simple and delicious—the hardest ingredient to come by is time.
Grab Your Gear
You can make cold brew coffee in any number of simple devices, from a jar to a pitcher to a French press. Companies like Toddy, Filtron and others make contraptions specifically designed for cold brewing, but assuming you have anything in your house that can hold liquid and coffee at the same time, you can basically use that.
Because cold-brew doesn't take electricity to make the coffee (other than grinding it—which of course you can do by hand, you carbon-neutral angel you!), you don't need anything else besides coffee, water, and a fine-mesh sieve and another filter-y cloth (cheesecloth, a brewer's hop bag, or a cloth coffee "sock" filter all work nicely) to get all those nasty, silty coffee particles out.
How To Do It Slow
The idea behind cold brew is that you not only serve it cold, you brew it cold—or rather, at room temperature. So instead of using heat to extract the coffee into drinkable goodness, we rely on time. Set aside a good chunk of time—most people just leave their cold-brew to extract overnight—and be ready for the goods about 12 hours after you deploy the water into the coffee.
Cold brew coffee is also easily adaptable to whatever sized vessel you're using, though if you're only relying on a standard Mason jar or French press carafe, you won't end up with a whole lot of concentrate. Find yourself a pitcher you like (and a comparable sized vessel to help you filter the brew twice with.)
Measure out a ratio of roughly 1 part coffee to 4.5 parts water to make your concentrate. E.g., if you're using a 64 ounce, or 8 cup, container, you'll want to measure out about 1.5 cups of medium-coarsely ground coffee. (Grind it fairly coarsely to help make it easier to filter out the particles in your final brew—your overnight steep should give it plenty of time to extract all the flavor. Gently mix the coffee into the water, making sure all the grounds get saturated, and leave the mixture to steep for the next 12 hours.
Once your coffee has steeped, you can first filter your coffee through your kitchen sieve (or French press screen if you're using a press) and into another vessel. Dump any grounds that remain in the original brewer and filter the coffee back into the first vessel, this time through a more fine-screened cloth such as cheesecloth. Dump those grounds, too.
Now you've got a concentrate upon which to base glass after glass of delicious cold coffee, whether you drink it at fridge-temp or over ice. It wants to be diluted before you drink it—try a ratio of 1 part concentrate to 3 parts water and attenuate to taste. You can keep this bad boy in the fridge for up to about two weeks, adjusting it to your preferences with water, milk, ice, cream, or whatever's your warm-weather pleasure. Sit back and relax and congratulate yourself on the off-the-grid deliciousness you've concocted.