In a blender, combine strawberries, orange juice and cinnamon; cover and process until smooth.
Transfer to a large saucepan; add the tapioca and let stand for 5 minutes. Bring to a boil; boil and stir for 2 minutes. Remove from the heat; stir in buttermilk, sugar, lemon juice and zest. Refrigerate. Garnish with whipped cream or yogurt and mint if desired.
Editor's Note: Hollowed-out honeydew or cantaloupe halves make fun serving bowls for this soup.