Wash lemon grass and cut in half lengthwise. Bring to the boil briefly together with sugar and 100 ml water (sugar must be dissolved) and allow to cool. Remove the seeds from the melon, remove the flesh from the skin and puree. Mix with sugar syrup and lime juice
Place in a wide bowl and freeze for 8-12 hours. Stir every 30 minutes for the first 6-8 hours. Beat the egg whites with the whisks of the hand mixer until stiff. After approx. 2 hours add to the sorbet and fold in
Divide approx. 1/4 sorbet into 4 chilled glasses (approx. 150 ml content). Refreeze the rest of the sorbet and use it later. Keeps for 6-8 weeks. Pour in Prosecco and decorate with lemon balm
Waiting time approx. 10 hours