In a large saucepan, bring broth to a boil over medium-high heat. Stir in rice, reduce heat, and simmer for about 8 minutes. Stir in sorrel and return to a boil. Remove from heat and puree in batches in a blender or food processor or using an immersion blender.
Return to medium-low heat and stir in cream, salt, and pepper. Heat through and serve.