Fill a highball glass with ice cubes almost to the rim.
Pour 60ml white rum over the ice.
Top with 120ml ginger beer, pouring gently down the side of the glass to preserve carbonation.
Stir briefly with a bar spoon - two or three slow rotations only.
Express a lemon peel over the surface to release the oils, run it around the rim, and place it on the edge of the glass as garnish.
Pouring the ginger beer down the side of the glass rather than directly over the ice minimises agitation and keeps the fizz alive longer - essential for a highball that relies on carbonation for its signature zip.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including A Furlong Too Late.