Temperature, for instance, is one of the key details that Japanese bartenders have mastered. As a highball is meant to be enjoyed with food more than on its own, it has to be served very cold, and at half the strength of a neat whisky. Ice is the key to achieving this.
The glasses used to hold a highball and the sparkling water or soda are also usually kept in a freezer to make sure the drink is served as it should be — ice cold. How you pour the soda water makes a difference too.
"Ice is important for highball, but most important thing for making a highball should be how you pour soda water," says Ueno. "You must pour it with no wave, fast enough between ice and inside of glassware so you don't really need to stir to mix it."
Then, there’s the proportions. While a highball in America usually involves average whisky doused with a splash of soda, the Japanese-inspired version is more refined. The common practice is to use three parts of (filtered) water to one part of whisky, to bring down the strength of the alcohol so the drink won’t overpower the food. Fresh fruits are often used as garnish, specifically paired to the flavour profile of the whisky used.
With highballs as good as these, save the whisky on the rocks for after dinner. This cocktail has gone past dive bar standards to come into its own.