Method

• 1.
  Start by making a simple sugar syrup. Place sugar in a small heatproof bowl and pour over 50ml boiling water, stir to dissolve, and set aside to cool completely. (This makes slightly more than you will need, but it can be kept in the fridge for later use.)
• 2.
  In a jug or cocktail shaker, add the rum, mint and 32ml of the sugar syrup, and use a muddler or the end of a rolling pin to crush the mint into the rum. Strain the mixture into a jug or jar.
• 3.
  Cut the limes into quarters and add to the jug or cocktail shaker with a pinch of salt flakes. Crush together using the muddler to extract the juice. Return the strained mint mixture to the jug and stir well to combine. Chill until ready to serve.
• 4.
  To serve, fill 4 glasses with lots of crushed ice and divide the drink among the glasses. Top with soda, and garnish with mint and lime.