Peel the papaya. Cut it in half and scoop out the seeds. Slice the skin from the grapefruit. Peel and chop the banana into chunks.
Pop everything into your blender with a cupful of ice and 250ml water. Whizz till smooth, adding more water if you need to.
Ripe and ready
When you unpack your box, you can put your papaya and banana together in a bowl or paper bag and leave them for a few days to help ripen the papaya.