Place the peaches and basil in a medium bowl and set it aside. Combine the lime zest, sugar and 1 cup water in a medium saucepan. Bring to a boil, stirring to dissolve the sugar. Lower the heat and simmer for 2 minutes. Then pour the hot syrup over the peaches and basil. Cover and chill for 2 hours.
Serve the peaches in bowls, garnished with a dollop of creme fraeche, if desired.