Remove the peel from the rhubarb, cut into pieces, boil with the juice of one lemon, water, wine, sugar and spices until soft, bind with cornstarch mixed in a little water. Pour into a large enough bowl and leave to cool. Pour into a large enough bowl and set aside to cool.
Whip the cream briefly, add the cream stiffener and vanilla sugar, whip until half stiff, fold in the liqueur and brandy. Serve the sauce well chilled.
Tip: Always use aromatic spices to refine your dishes!