Add lime juice, sugar and eight mint leaves to a cocktail shaker. Use the end of a wooden spoon or cocktail muddler to bash (or muddle) the mint into the lime juice and sugar. This releases oils from the mint and helps the sugar dissolve into the lime juice.
Add rum, stir well then pour into a glass filled with ice, leaving about an inch of room then top with club soda. Garnish with extra mint leaves and a lime slice.
Notes and Tips
To make enough for four people follow these amounts:
1/2 cup freshly squeezed lime juice
3 tablespoons sugar
32 fresh mint leaves, plus more for garnish
1 cup white rum
4 cups ice
1/2 cup club soda
4 lime slices for garnish