1 tbs brown sugar
2 tbs chopped mint leaves
2 limes, quartered
Crushed ice
1 shot (30ml) each rum and gin
Soda water, to serve

How to:

Place sugar, mint and lime in a cocktail shaker.
Put one end of a wooden rolling pin into the shaker and gently bash or 'muddle' for a couple of minutes until the mint has broken down and the limes have released their juice.
Add the ice, rum and gin. Shake well to combine, then divide among glasses and top up with soda water.