Cut the melon into eighths and cut out the flesh as triangles. Cut lemon balm leaves (some are kept for decoration) into strips. Mix with lemon juice and zest.
Marinate the melon pieces for about 1 hour. Wash the grapes, dab dry and cut in half. Then remove the seeds. Peel and slice the bananas. Mix melon with juice, grapes, bananas, sugar and vanilla sugar.
Roast almond slivers in a pan without fat until golden brown. Arrange the fruit salad on four plates, sprinkle with almond slivers. Decorate with balm leaves.