Dissolve the sugar with 4 tablespoons of water over medium heat and allow to cool. Halve lemons lengthwise and squeeze them carefully on a lemon squeezer. Remove the remaining pulp. Measure out about 100 ml juice. Mix yoghurt, lemon juice and sugar solution. Whip the cream until stiff and fold into the yoghurt. Place the cream in the freezer and stir every 30 minutes until the cream is ready to be sprayed.
Set aside some lemon balm for decoration. Pluck the remaining leaves from the stems, wash and chop finely. Stir into the cream. Pour the cream into a piping bag with a large star-shaped spout and squirt into the lemon halves. Let it freeze again for at least 5-6 hours. Arrange 2 lemon halves on each plate and serve decorated with lemon balm
waiting time approx. 9 hours