My spouse has spent I-don't-know-how-many hours tinkering with his cold-brew, which is now my favorite coffee anywhere. He finally typed it up for us:
There are two great things about making cold-brew coffee. First, this method results in a very low-acid brew. The coffee is sweet and chocolatey, and great for mornings or before a long run. Second, once you make a pitcher of this, you've got coffee in an instant for at least a week.
The key here is the nut-milk bag. I've tried this just pouring the coffee through a filter or cheese cloth, and it takes forever and creates a big mess. With the bag, this is no harder than making a pot of tea.
4 cups cold water
1 large bowl
1 large pitcher
(Optional) large coffee filter or cheesecloth + mesh strainer
This is a coffee-inefficient brew method, but fortunately you can use an inexpensive preground coffee. I usually use a store brand french roast.works great, too. There's no reason you can't grind your own, but I don't think it is really worth the effort here.
Here goes nothing:
1. Put the coffee in the nut milk bag, and the nut milk bag and the water in the bowl.
2. (Optional) Put something heavy on the nut-milk bag to keep it below the surface.
3. Put the coffee (in the nut milk bag in the water in the bowl) in the refrigerator for 12-18 hours, You can stir it up once or twice if you remember. Set a phone alarm so you don't let it sit too long.
4. Remove the nut milk bag from the bowl, giving it a good two-handed squeeze to get the last of the good stuff out.
5. Ladle or pour the coffee concentrate from the bowl to the pitcher. A bowl with a spout makes this easier.
6. (Highly optional) If you want to be really persnickety about this (like me), put a large coffee filter or cheese cloth in a strainer and pour the coffee through that into the pitcher to remove any fine sediment that got through the nut milk bag.
Now you've got a coffee concentrate that will last for a week in the fridge, probably two if you get a hermetic pitcher.
The recipe can be scaled as long as you maintain the water-to-coffee ratio.
Again, it's a concentrate, so when ready to enjoy, pour over ice and add an equal amount water. (Or, if your name is "Sarah," about 2 parts water to one part concentrate,) Milk and simple syrup are optional but delicious.