Well, they both have their place, but there are pros and cons. Iced filter coffee requires simply ice and a ratio adjustment and is finished in about 5 minutes. It's bursting with subtle flavour and nuance. However, the acidity tends to be higher due to the hot water used when brewing, and it's often not as smooth as immersion brew.
On the other hand, immersion brew is super simple, requires only a brief amount of forethought, and can produce some of the smoothest cold coffee you've ever drunk. However, it's easy to end up with a muddy coffee that lacks nuanced tasting notes with improper technique.
So we'll go over both methods, and you can brew them at home to decide the winner!
Let's start with iced filter coffee.
Now it's a good idea to increase your regular dose of coffee by at least 25-33%, as the ice will dilute it some. So taking our standard brew ratio of 15g of coffee to 250g water, we'll up the amount of coffee to 20g.
You'll also want to lower the temperature of your water slightly to reduce ice meltage. So instead of 92c, we'll be brewing at 90c. If possible, refrigerate your serving carafe for about 5 minutes before use.
Add as much ice as you can fit in the serving vessel, and place your dripper overtop with a pre-rinsed filter. Add 20g of coffee, and then brew your coffee as standard. We're using a V60 brewer here, so we'll follow our standard V60 Recipe.
A note about ice in coffee: Ice in coffee often melts rather quickly. That's because typically, the ice cubes themselves are relatively small, and with a smaller surface area, it dissolves quicker. To get around this, try to use or source larger ice cubes. You can often find silicone 2-inch ice cube trays in bar and cooking equipment stores. Not only will these dissolved slower because they have much more surface area, but you often only need one for glass, so you run out less often. Plus, they look fantastic.
Our favorite way to enjoy this iced brew is black or with just a dash of milk. Preferably in a hammock, on a sunny day.
Immersion brew has a little more creative freedom in the brewing vessel used. You can use anything from a purpose-built brewing vessel like the Hario Filter-in Immersion bottle or even a mason jar with a loose leave tea brewer. While you could add the grounds and water and stir it, we generally don't recommend this. The reason is, the coffee will sink to the bottom overnight and not extract completely, leaving you with that muddy cup that we spoke about earlier.
So, how much coffee do we use?
Well, you can use your standard brew ratio and increase it just like we did for the iced Hario. However, as immersion brewing takes longer, it's a good idea to do tastings every 4-8 hours to see what timeframe works best for you. Over here, we're going to be using the Hario Filter-in immersion bottle, which has a capacity of 750ml. So we'll tweak our standard ratio of 45g coffee to 750g water to about 55g coffee and 750g water. We're aiming for an 8-hour brew time.
So add your coffee to your suspended filter, and then start pouring water over the top. The beauty in the Hario bottle is that the coffee is suspended in the middle of the water, allowing for the evenest extraction. Once you've added all the coffee and water, cork it and give a gentle shake to begin the extraction process. Now add a tape label of the time you put it in the fridge and come back in 4-8 hour increments. Taste a little bit in a glass to see if the flavour is perfect for you, and remove the coffee and filter once you're happy!
This immersion brewed coffee will generally last about a week, but obviously, the fresher, the better, so try and only make enough for 3 or 4 days.