In a 2-quart heavy pot, combine the apples, peach, water, sugar, lemon juice, orange juice, 1/4 cup mint leaves and lemon zest. Bring to a boil over medium-high heat, then reduce heat to mediumlow and simmer uncovered for 20 minutes.
Remove from the heat and puree with an immersion blender, or in batches in a blender. (Use caution when pureeing hot liquids.) Transfer to a clean container and refrigerate until thoroughly chilled, at least 2 hours.
Stir the Champagne into the soup. Ladle into 6 small, chilled bowls, and garnish each with a teaspoon of mint and a teaspoon of chopped crystallized ginger. Serve immediately, either as a firstcourse or a dessert.
Yield: 1 quart: about 4 - 6 servings