Iced coffee: How to make the perfect frappé, according to top London baristas

It's so hot right now that keeping cool is at a premium. The solution, in the hours before a cold beer is acceptable? Iced coffee. Set your morning cuppa from scald to cold, and face the blistering day with a temperature-appropriate tall glass.

Of course, whipping up the perfect frappé does not come naturally to most of us. Never fear, beginners, we have you covered. “A good starting point is an overnight cold brew,” says Anson Goodge, at Ozone Coffee Roasters. Place the coarsely ground coffee you normally use in your cafetière and simply leave to brew in cold water overnight, pushing the plunger down in the morning. Premium basic.

The essential ingredients are simple, says Angelos Papamichael, head barista at Rye By The Water in Brentford. You’ll need excellent espresso and quality milk (an 8oz drink needs a 1.5 shot espresso, he says, while 12oz needs two shots of espresso).

Cold milk from the fridge goes over ice so it doesn’t melt quickly. “Pour your espresso over the top, as it should always go in last,” says Papamichael.

But what if you wake up with an urge for a chilly caffeine hit to start your day, only to discover — shock, horror — you forgot the overnight brew? If you’re short on time “brew hot and cool down afterwards”, says Goodge. Essentially brew as normal then pour straight on to ice. “We advise that people use one part coffee to four parts water,” says Goodge. This is because you’ll need a stronger brew to counteract the ice diluting your coffee, leaving it weak. Add milk for an iced latte.

Once you’ve mastered that, you’ll want to kick things up a notch. “A better quality cold brewer is one way of doing this,” says Goodge. He recommends a Toddy home brew coffee filter — used at Ozone — which have nylon filters. “The brew gets really clear and you don’t get little coffee grinds floating around your cup.” For those looking for even more advanced equipment, V60 and Kalita coffee drippers also come highly spoken of, providing clear coffee purified with a paper filter.

Indeed, the more tricks of the trade you apply, the better the brew. Papamichael suggests adding marshmallows on top of your iced latte — or 50ml of coffee liqueur if you’re feeling feisty.

Goodge doesn’t rate London tap water, so invest in your own water filter or buy it (glass) bottled. “Cold brew coffee with tonic water and a slice of lemon is also super refreshing,” says Goodge. “The fizz from the tonic is very nice, that little bit of sourness you get from the lemon makes it a summertime drink.”

He recommends “playing around with milks” — banana-flavoured almond milk, anyone? — and fruits. Frozen strawberries are a hot tip.

Lastly, you’ll want to think about the coffee bean itself. “I tend to look at coffee by parts of the world,” says Goodge. “If you like strong, chocolatey and nutty profiles, you’ll want to stick to South American beans, like those from Brazil, Colombia and Nicaragua. If you like it fruity, look to African countries, such as Ethiopia or Kenya.” Buy responsibly and ethically, naturally (look for a Fairtrade logo).