12 cups 1-inch pieces seeded or seedless watermelon (from about 7 pounds)
2 tablespoons cornstarch
2 cups Johannisberg Riesling wine
1/3 cup (or more) sugar
2 cups (lightly packed) fresh mint leaves (from about 1 large bunch)
1/2 teaspoon salt
1/4 teaspoon cayenne pepper
1 cup 1/4-inch cubes seeded or seedless watermelon
1/2 cup crème fraîche or sour cream, stirred to loosen
Fresh mint sprigs
Directions
Working in batches, puree 12 cups watermelon in processor until smooth. Strain puree into large bowl. Transfer 1 cup puree to small bowl; cover and chill. Whisk cornstarch into remaining puree. Bring wine and 1/3 cup sugar to simmer in large pot, stirring until sugar dissolves. Simmer 3 minutes. Add watermelon-cornstarch mixture; bring to boil, whisking. Transfer soup to bowl; stir in 2 cups mint. Cool to room temperature, whisking occasionally, about 1 hour.
Strain soup into another bowl, pressing on solids to extract as much liquid as possible. Stir in salt and cayenne. Add more sugar, if desired. Chill until cold, at least 4 hours and up to 1 day.
Whisk reserved 1 cup watermelon puree into soup. Ladle soup into 8 bowls. Mound 2 tablespoons cubed watermelon in center of each bowl. Drizzle soup with crème fraîche. Garnish with mint sprigs.
