Pour the oil into a large saucepan.
As soon as the oil is hot, add the squash seeds.
When the seeds are crisp and brown, pop onto a plate with kitchen paper using a slotted spoon.
Sprinkle over the salt and mango powder.
To the same oil, add the ginger and cook for a minute.
Add the saffron and stir through.
Now add the squash and fry for a few minutes.
As soon as the squash has some colour, pour in the water and grapefruit juice and add the zest.
Mix and leave to boil.
As soon as it has boiled, simmer on medium heat for 20 minutes till the squash has cooked right through.
Take off the heat and use a stick blender to make smooth.
Serve the soup with a dollop of soured cream, some squash seeds and a drizzle of olive oil.
