Freeze the ice cubes with 1 lemon balm leaf each. Peel oranges and grapefruits so that the white skin is completely removed. Cut the fillets out of the parting skins and squeeze the juice out of the rest.
Wash kumquats thoroughly and cut into slices. Mix the fillets and kumquat slices with sugar and orange liqueur and leave to stand for 1 hour. Top up with well chilled sparkling wine and wine. Add ice cubes and some lemon balm leaves.