In a large, non-reactive saucepan, combine the lemon rind, lemon juice, ⅔ cup sugar, water, and white wine.
Warm over medium-low heat, stirring constantly until the sugar is fully dissolved.
Do not let it boil. 2.
While the lemon base is warming, wash, stem, and pit the cherries.
Set aside 18 of the most beautiful cherries for garnish.
Add the rest of the cherries to the saucepan. 3.
Bring the mixture to a gentle simmer and cook until the cherries are very soft, about 10-15 minutes. Carefully transfer the hot mixture to a blender and purée until silky smooth. Return the purée to the saucepan. 4.
In a separate small bowl, lightly whisk the egg yolks. Very slowly, pour about half a cup of the warm cherry purée into the egg yolks while whisking constantly to temper them.
Pour the tempered egg yolk mixture back into the saucepan. 5.
Place the saucepan over very low heat.
Whisk gently and continuously for 3-5 minutes as the soup thickens to a custard-like consistency.
Do not let it boil, or the eggs will curdle. 6.
Remove the soup from the heat and allow it to cool at room temperature for about 20 minutes, stirring occasionally.
Once it's no longer steaming, stir in the ice cubes to rapidly cool it down.
Once the ice has melted, cover and transfer the soup to the refrigerator to chill for at least one hour, or until completely cold. 7.
While the soup chills, prepare the sweetened sour cream.
In a small bowl, combine the sour cream and 2 to 3 tablespoons (45 ml / 1.5 fl oz) of sugar.
Whisk until smooth and the sugar has dissolved. 8. To serve, divide the 18 reserved cherries among 6 chilled bowls. Ladle the cold soup over the cherries.
Top each serving with a generous dollop of the sweetened sour cream and enjoy immediately.
