Cold-Brewed Vietnamese Iced Coffee
Ok, your first response to "cold-brewing" was probably "what the.... you can't cold-brew coffee!" Everything you hear about brewing coffee, and particularly espresso, talks about getting the temperature hot enough to do the job right.
But when we talk about applying heat to coffee, we are really talking about fast brewing, or brewing-on-demand. We are talking about extracting the flavor elements quickly. That is NOT always necessary, though. If you are willing to do your brewing in advance of when you want to drink your coffee, then cold-brewing is an option.
Cold versus Hot
Cold brewing takes time. However, it dissolves through the grounds only certain elements of the coffee. Surprisingly enough, about 90% of the flavor elements and the normal caffeine content come through this way, while only about 15% of the oils and acids will. It WILL change the taste of your coffee, but not the way you might think. It will strongly concentrate those most volatile flavor elements that most people like, making "super-flavor" coffee. The flavor elements you like about a given coffee will probably be up to 200% as strong, yet the overall brew will have far less bite and acidity.
Is this a good thing? For people who like the acid and bite, which is part of the attraction of strong coffee, they may not like cold brewing. Other people take one sip and say "Oh my God, that is fantastic." Our recommendation is simple: Try it once or twice and see if you like it. Also, different varieties will respond to cold brewing differently, so it's hard to predict.
Easy cold-brewing for small quantities
It takes no more total time to prepare coffee this way than most hot brewing methods. It just takes more time for it to brew, so plan ahead.
Items needed: (To make enough for 2-3 glasses of iced coffee)
Measure a 1/4 to 1/3 cup (5-6 tablespoons) of coffee into the brewing glass. Add about a cup and a half of room-temperature water (bottled water or filtered water will taste best). Stir the mixture until it is even and there are no lumps. You don't have to be really precise on these measurements. Just make sure you have about 4:1 water to coffee.
Put some sort of lid on the container/container to keep the mixture clean, or use a canister-type container as we show here. Let it sit a minimum of 3 hours. It can sit overnight if you like (some people do this), but we find 3-4 hours is fine.
When ready, pour the mixture through the stainless steel strainer into the second container. Clean the first glass to rinse out any grounds. Then pour the coffee back from the second glass into the first glass THROUGH THE CUP SECTION OF THE FILTER SET. This removes the fine grinds. It may be necessary to stop pouring once to rinse the filter cup to clear the tiny holes at the bottom.
The jars shown below are actually the set I use for making a pitcher of coffee, but the principle is the same, only the quantity changes.
Pour the final mixture into your storage container and put it in the fridge. That's it!
This mixture is possibly 2-3 times as strong as you will want to drink it. Dilute with an equal amount of water to start. Serve over ice. If the mixture is too strong, add water water to dilute. Add cream and sugar at the time of serving. If you want to serve this coffee Vietnamese style, do the following:
Spoon a tablespoon of sweetened condensed milk into your glass. Fill the glass with cracked or small-cube ice, to the top. Pour the coffee (undiluted) over the ice but don't fill the cup. Stir the mixture around enough to mix the thick condensed milk up into the coffee. Then sip the coffee from the glass, don't use a straw. It's strong and sweet and cold. Some Vietnamese insist that the condensed milk is not needed in iced coffee. Whatever, follow your tastes!
Cold-brewing in quantity
The principles are exactly the same, use about 4:1 water to coffee grounds. A 500-gram bag of Trung Nguyen coffee should be mixed with 10-12 cups of water, as a general guideline.
Grind your own whole beans if you want, make it a medium coarse grind for better results. Use larger containers. It will take longer to strain it, and you should be prepared to do it over a mat or the sink so that you don't stain anything with any spilled coffee or grounds.