Over the years, we've seen a lot of different ingredients getting mixed into coffee. More often than not, these additions tend to be creamy and a little heavy, turning the regular cup of joe into a milky confection. But that trend looks to be reversing, with the discovery that adding a little tonic water to your espresso (or cold-brew!) yields a drink that's crisp and light, with a complexity that puts it on par with some of our favorite summer cocktails. The espresso tonic has started popping up on menus at trendy coffee shops around New York, and we've even heard that Stumptown has their own variation in the works. Here at CE HQ, we're officially hooked - and we're more than a little happy that this is a mixed drink we can enjoy any time of the day.