Crush the cardamom pods in a pestle and mortar (if using) and discard the green husks. Bash the seeds to a fine powder and set aside. Cut the juicy flesh off the mangos (the riper they are, the better), leaving the stone in the middle and trimming away all the skin. Place the mango flesh and any juices into a blander with the yoghurt, ice cubes, 1 tablespoon of honey and the ground cardamom (if using). Blitz until smooth, have a taste, and add a little more honey, if needed. Serve immediately.