This ultra-refreshing soup is chilled instantly by adding shaved ice. If you don't have an ice shaver, you could crush ice in the food processor. Or, if you have a little time up your sleeve, freeze the young coconut water in a shallow tray, then scrape it into crystals with a fork and use this instead - made this way it's a triple textural coconut whammy.
Note Young coconuts are also sold as drinking coconuts in greengrocers and supermarkets. To open one, place it flat-side down on a hard surface and carefully cut off the dome-shaped lid with the heel of a large knife or cleaver. You'll need to use a bit of force. Pour out the liquid and remove the flesh with a spoon.