Boil sugar and water in a wide dab. Wash the lemon and cut the peel thinly. Add to saucepan and do 15 to 20 minutes, stirring frequently. The liquid should have reduced by half. Remove the lemon peel and cool the liquid.
Squeeze the lemon. Stir the juice of one lemon, peppermint liqueur and sparkling wine into the liquid. Put the mixture in a cold-resistant bowl in the freezer or the freezer of the refrigerator.
Stir the sorbet gently with a stirring spoon every half hour for the first 2 hours, then three more times to give it a fluffy texture as it freezes.
After about 8 hours, the sorbet is ready. Using an ice cream scoop, form the number of balls indicated above from the quantity and arrange in chilled dessert bowls. Decorate with mint leaves and bring to the table on the spot.
Tips & Tricks:
USE. If you use the blue orange liqueur (sold under Curacao blue), the sorbet gets a great color.