Don't miss out on our special Christmas issue with free 2023 calendar - subscribe by 11 October!
Muddle the lime juice, sugar and mint leaves in a small jug, crushing the mint as you go – you can use the end of a rolling pin for this. Pour into a tall glass and add a handful of ice.
Pour over the rum, stirring with a long-handled spoon. Top up with soda water, garnish with mint and serve.