Step 1

Combine half the peaches, the sugar, mint sprigs, salt, and ¼ cup water in a medium saucepan. Bring to a boil over medium high heat, stirring until the sugar dissolves. Remove mint sprigs. Pour hot syrup into a food processor or blender. Add the lemon juice and remaining peaches; puree until smooth.

Step 2

Pour the puree into a 9-inch square metal baking dish. Stir in the prosecco. Cover and freeze for 3 hours more, scraping the mixture with a fork every hour or so, until the mixture is frozen and scraped into fluffy, icy crystals. Cover and freeze for 8 hours more before serving.