Cut the avocados in half length ways, remove the stones and scoop the flesh into blender or food processor. Add half of the cream and process until smooth. Add half of the remaining cream and process again until just combined. Place the chicken stock in a medium sized saucepan and bring slowly to the boil.
Remove from the heat and gradually whisk in the avocado puree.
Add the sherry. Heat gently, but do not boil.
Season with salt. Remove from the heat. Pour into a warmed soup tureen.
Serve hot or cold with the remaining cream swirled over the top and chopped coriander sprinkled over.