Note Young coconuts have soft flesh and are filled with liquid suitable for drinking. They are usually sold with the outer green shell removed and the white fibrous husk partly cut away; they are available from Asian grocers and some supermarkets. To open a young coconut, place it flat-side down on a surface and carefully cut off the dome-shaped lid with the heel of a large knife. You'll need to use a bit of force. Pour out the liquid (or drink it with a straw) and remove the flesh with a spoon.
This dessert is perfectly refreshing on a hot summer's day. You'll need to begin this recipe a day ahead.