Pick any thick stalks out of the watercress and add the tender leaves and sprigs to your blender. Quarter the pears, slice out the cores and seeds and add the pears to the watercress.
Pop the stones out of the Medjool dates and drop the dates into the blender. Squeeze in the lime juice. Shake the coconut milk tin and then pour it into the blender. Add a few ice cubes and 150ml water. Blitz till smooth.