Whip the Yoghurt and add the water to it. Separate the curry leaves from the stalk. In a bowl hop the curry leaves along with ginger and green chillies. Then add few crushed ice cubes along with salt, and blend all the ingredients together. Puree until smooth. If you wish ,strain the mixture through a fine-mesh strainer. Transfer to a large pitcher and chill in the refrigerator for 10-15 minutes. Fill tall glasses halfway with the ice cubes. Pour the mix into these glasses. On the top and coriander leaves.