The sun's finally out in London, so it's time to repost last summer's cheap, easy, no-mess cold-brew coffee technique. This is the best cup of coffee you're likely to drink this summer.
I bought a $10 "nut-milk" bag and a plastic pitcher. Before bed, I ground up about 15 Aeropress scoops' (570 ml) worth of espresso roast coffee -- the $20 Krups grinder is fine for this, take no notice of people who claim the blade overheats and burns the beans; it doesn't even get warm -- 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.
In the morning, I took the bag out of the pitcher and gave it a good squeeze to get the liquor out of the mush inside. Add water to the pitcher to fill to the brim and voila, amazing cold-brew. You can dilute it 1:1 or even further.
Cleanup was easy: invert the bag over a composter, trashcan or garbage disposal, rinse off the bag, and you're ready to go.
This produced very, very good coffee concentrate, with only a little grit settled into the bottom 3mm of the pitcher (easy to avoid). It may just be the cheapest and easiest cold-brewing method I've yet tried.
(Image: cold brew experiment, Dennis Tang, CC-BY-SA)