Preheat the oven to 90ºC. Use the Thin Slicing Disc of a Compact Food Processor to thinly slice the limes. Lay them out on a metal wire rack over a large baking tray, scatter with icing sugar and bake for 3-4 hours.
Tip the caster sugar and water into a small saucepan and put it over a high heat. Add the spices and honey and let the mix bubble until all of the sugar has dissolved and the liquid has thickened slightly. Remove from the heat and leave to cool with the spices in the liquid. Strain the spices from the cooled sugar syrup.
Divide the mint and lime between 2 glasses and muddle. Pour 35ml of rum and 25ml of the spiced syrup into each glass. Top the glass with ice, stir, then slowly pour over the soda water. Garnish with mint and a dried lime slice and serve. Serves 2 (with extra syrup)