Saute the onion and garlic in a saucepan with a little water or stock for 4 minutes. Add the turnip and sweet potato, and saute for a further 3 minutes. Add the rest of the stock, and simmer for 10 minutes. Stir in the courgette and kale, and simmer for 5 minutes. Add the spinach in at the end, and simmer for another minute. Pour the soup mixture into the blender or food processor, and blend till smooth. Return to the saucepan with heat on low, and add some freshly chopped curly parsley to garnish.