Cook the cherries In a pot, combine cherries, 4 cups water, sugar, cinnamon stick, and cloves. Bring to a boil, then simmer for 10–15 minutes until cherries are soft.
Thicken the soup In a small bowl, mix cornstarch with ¼ cup cold water to make a slurry. Slowly stir into the hot cherry soup and simmer for 2–3 minutes until slightly thickened. Remove from heat.
Cool the soup Let the soup cool to room temperature, then refrigerate for at least 2–3 hours until chilled.
Add sour cream Before serving, whisk sour cream into the chilled soup until smooth. Adjust sweetness or add a little lemon juice/zest if desired.
Serve Serve cold in bowls, garnished with a few whole cherries or a sprinkle of cinnamon.
