Fill a highball glass with ice cubes.
Pour 45ml of light rum over the ice.
Add 150ml of fresh orange juice.
Stir gently to combine.
Garnish with an orange slice and serve immediately.
Using freshly squeezed orange juice rather than carton juice makes a noticeable difference here - the brightness of fresh citrus lifts the subtle grassy notes of light rum in a way that processed juice simply cannot.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Rum Screwdriver.