Curly kale leaves should look fresh and crisp, with no sign of yellowing ... For best results, either cook very briefly in a large volume of ready-boiling water or stir-fry as a side dish.
Then add the kale and cook for another 4 minutes. Using a jug blender or a stick blender blend the soup for a good few minutes until everything is well blitzed and smooth. Return to the heat and ...