Lightly crush 4 cardamom pods and shake the seeds into a pestle and mortar. Grind to a fine powder. No pestle and mortar? Use a small bowl and a rolling pin or the bottom of a jam jar. Tip the ground cardamom seeds into your blender.
Slice the fat cheeks off the mango, then slice off the thinner sides. Slice the flesh off the skin and add to the blender. Slice as much flesh off the stone as you can and add that too.
Add the spinach and yogurt to the blender. Pour in 250ml cold water and add a couple of ice cubes. Blitz till smooth and creamy.