Dark and Stormy

Fill a tall glass with ice.

Pour in the lime juice, then the ginger beer.

Stir once, gently, to combine them.

Hold a bar spoon just above the surface, curved side up, and pour the rum slowly over the back of it.

The rum should sit as a distinct dark layer on top. If it sinks, you poured too fast or the glass is too warm.

Serve with the lime wedge and let the drinker stir it in when they want to.