This is not just for Christmas, but I always associate clementines with Christmas, and the addition of spices also lends a festive feel to this delightful soup. It is so easy to make and makes an elegant and colourful soup starter for any formal or special dinner. The smell is redolent of Christmas pasts for me - plus, the vibrant colours just "leap" out of the bowls! Serve it with an assortment of interesting little dinner rolls and maybe some citrus flavoured butter. I have suggested 4 to 6 clementines - they vary so much in size - we like this with a real citrus tang to it, but please adjust the quantities of the clementines to suit your personal tastes. One final tip - do try to use the crushed coriander seeds rather then the ground coriander, they add a complex and interesting flavour to the soup, as well as a wonderful fragrance!