Experiment with the amount of cola syrup you add to the ice - and for an extra kick, throw in a splash of golden rum.
600 gmice cubesTo serve:lime wedgesCola syrup400 gmcaster sugar75 gmbrown sugarGratedrind and juice of 1 lemon, 1 lime and 1 orange1cinnamon quill1 tspfinely grated ginger½star anise½ tspcoriander seeds¼ tspdried lavender1/8 tspfinely grated nutmeg½vanilla bean, split, seeds scraped½ tspcitric acid
For cola syrup, stir ingredients, except juices, vanilla and citric acid, with 300ml water in a saucepan over medium heat to dissolve sugar, bring to the simmer, then reduce heat to low and simmer to develop flavours (5 minutes). Cool (about 1 hour), then stir in juices, vanilla and citric acid, strain through a fine sieve and refrigerate in a sealed bottle. Makes about 600ml. Cola syrup will keep for a month.
To serve, finely crush ice in a food processor and pack into serving cups or dishes, drizzle with cola syrup and squeeze lime juice over the top.