For the prickly pear salad, cut the flesh of the figs and the melon into cubes. Dissolve the sugar in the 4 tablespoons of boiling water and let it cool.
Stir in the lemon juice and the liqueur and pour the sauce over the fruit.
Leave the fruit salad in the refrigerator for an hour and garnish with the stiffly whipped sweetened whipped cream before serving.