With a blender. The water should be fairly hot. Put the desiccated coconut and half the water into the blender. Blend for 20–30 seconds, then squeeze and sieve the resulting mush. Put the squeezed coconut back into the blender with the rest of the hot water, and repeat.
Without a blender. Simmer the desiccated coconut and water in a pan for 4–5 minutes. Allow to cool a lit