British · Cocktail
A gin and tonic is mostly tonic, which is why the tonic matters nearly as much as the gin. One part gin to three parts tonic, and more ice than feels sensible.

Photo: Ivo Duarte Nogueira / Pexels
The one thing that matters
Pour the tonic down the side of the glass, not into the middle. That keeps the bubbles. And open it fresh. A tonic bottle that's been in the fridge two days is flat and there's no rescuing it.
Cheap tonic is sugar and quinine and it flattens whatever is above it. Spending four dollars more on the mixer changes the drink more than spending twenty more on the gin, which is not what anyone wants to hear after buying the gin.
Bombay is vapor-infused rather than boiled, so it comes out bright and citrus-led instead of tasting like a pine tree. That's the main way gin goes wrong for people who think they don't like gin.
Fill the glass to the brim with ice. A half-empty glass of ice melts fast and you're drinking warm tonic within minutes. Ice is not the enemy here; it's the whole cooling system.
Lime is standard, but a cucumber ribbon suits Bombay better, and a grapefruit peel is better still if you have one. Squeeze whatever you use over the glass first.
It goes with smoked salmon, olives, and anything you eat standing up at a party.