Additional shrimp and cucumb -r slices for garnish In a large bowl, whisk together the buttermilk, mustard, salt and sugar. Add the chopped shrimp, chopped cucumber, and chives and stir until well combined. Chill the soup, covered, for 3 hours or until very cold. Garnish each serving with a whole shrimp and a slice of cucumber. Makes about 5 cups. a 1944 Gourmet Mag. favorite.