Saute onions and celery in butter until soft. Sprinkle flour over vegetables and cook 1 minute, stirring to coat. Add stock and peanut butter; simmer 20 minutes.

Allow mixture to cool 15 minutes, then puree in batches in blender. (The soup may be made ahead to this point and refrigerated.) To serve, reheat in saucepan over medium heat. Correct seasoning with salt and lemon juice. Serve with a dash of cream and a sprinkling of peanuts.