Cold-Brewed Coffee

Friends who've asked me what cold-brew is, how to make it, or if it's easy: this is for you.

I first learned about cold-brewed coffee from author Cory Doctorow's book, Homeland. Simply put, it's coffee that is made the same way one makes cold-brewed iced tea (by leaving the leaves in cold water for a long period of time, rather than in hot water for a short period of time). As Cory puts it, it's "cheap, easy, no-mess", and "the best cup of coffee you're likely to drink this summer."

Why? There are many reasons to drink cold-brew. Here's some:

• If you're wanting iced coffee, like I usually am, it's already cold, so no need for ice
• Because there's no ice, you don't get watered-down coffee
• The end product is a concentrate, which can be deluted 1:1 with cold or hot water, giving you more portability
• Hot water causes coffee grounds to excrete a chemical that is bitter, but cold water does not, giving a smoother, more pleasant flavour 
• Apparently, there's higher caffeine levels, but I'm not sure if that's just because it's a concentrate. More research is required
• If your end product is hot coffee, you don't need a coffee maker: just a source of boiling/hot water

How? Cory's method is super simple:

I bought a $10 "nut-milk" bag and a plastic pitcher. Every night before bed, I ground up about 15 Aeropress scoops' (570 ml) worth of espresso roast coffee — the $20 Krups grinder is fine for this, though I wouldn't use it with an actual espresso machine — leaving the beans coarse. I filled the bag with the grind, put it in the bottom of the empty pitcher like a huge tea-bag, and topped up the pitcher with tap water (distilled water would have been better — fewer dissolved solids means that it'll absorb more of the coffee solids, but that's not a huge difference). I wedged the top of the bag between the lid and the pitcher and stuck it in the fridge overnight.

Because I am the only person in the house who likes coffee (if Starbucks doesn't count), my method's slightly different. I put the coffee and water — roughly 1 part grounds to 3 parts water — in my one-litre french press coffee maker overnight, and the pour it in the morning. It's slightly inferior as you cant squeeze out the last bit of liquid, and you get a bit more of the silt.

Once you have brewed your coffee, you have many options. Experiment! Here's some that I've tried so far:

1. Straight coffee concentrate. Deliciously strong.
2. Coffee concentrate diluted 1:1 with ice water. The standard.
3. Coffee concentrate diluted 1:1 with boiling water. Very similar to hot americano or drip coffee, except that I actually like it.
4. Coffee concentrate diluted 1:1 with ice water, and a touch of almond milk. I used almond milk because of it's longer shelf life, plus the nutty flavour is a nice one.
5. Number 4, with 2ml of vanilla extract
6. Coffee concentrate diluted 1:1 with ice water, 2% milk, and mint extract.

Remember these key points:

1. 1:3 ratio of coffee to water
2. Water should be cold (room temperature or cooler)
3. If you're doing the grinding yourself, you want to use the coursest setting
4. Let it steep for 12-24 hours

Everything is variable! Play with the coffee:water ratio and figure out what's your favourite way to make it.