Remove skin and stone from avocados. Process the flesh in a food processor or blender until smooth. Add the cream and process, using pulse button, for several seconds or until mixture is just smooth.
Add stock, salt and pepper to taste, and lemon juice. Process until mixture is just smooth. Serve chilled or at room temperature, topped with a dollop of sour cream or cream and some chopped chives or sliced spring onions. If you wish to serve warm, heat gently.
Avocado soup should be served as soon as possible after being made. Even though this recipe contains lemon juice, the soup will eventually discolor.