Start by bringing the water and sugar to the boil in a saucepan, and let it boil until you have a clear syrup. Take the pan off the heat and add the elderflower. Cover the pan with plastic foil and let everything cool down. Then strain the syrup to remove the elderflower. Cut the peaches into wedges and skewer them with 2 skewers each. Grill over the binchotan until they begin to colour, brushing occasionally with the syrup during baking (use a brush). Serve the peach skewers with vanilla ice cream and top with a spoonful of elderflower syrup and a few drops of lime juice.