Cut the lime into 6 pieces. Carefully pick the mint leaves from the stalks and place in to a sturdy glass with the limes. Add the sugar syrup to taste: add 10ml sugar syrup for a sour cocktail and 20ml for a more balanced version.
Muddle the mint, limes and sugar syrup together, taking care not to tear or overly crush the mint leaves. Fill the glass with crushed ice and then add the rum and the soda water to fill the glass.
Stir together and serve with 2 straws.
«Take care not to crush the mint leaves too much as they will add a bitter flavour to the drink.»