In a medium saucepan, combine cherries, water, sugar, cinnamon stick and lemon peel. Bring to a boil, then reduce heat and simmer gently until cherries are just tender, about20 minutes. Dissolve the cornstarch in a small amount of cold water, add to the soup, cook and stir until thickened. Allow soup to cool slightly. Cover and chill for several hours or overnight. Before serving, remove cinnamon stick and lemon peel. Garnish each serving with sour cream, yogurt or buttermilk. Sprinkle with lemon zest.