Rinse the orange hot and pat dry. Cut into the narrowest possible slices with a bread slicer or sharp kitchen knife.
Stir the orange juice as well as the sugar in a large frying pan and spread the orange slices in it evenly against each other. Simmer the juice and sugar mixture over low heat for about fifteen minutes, until the orange slices are glazed and the liquid has almost completely cooked away. Remove from the heat and cool with the lid on.
For the mousse, soak the gelatin in cold water. Beat the yolks with champagne (1), sugar (1) and the juice of one lemon in a metal bowl in a hot water bath until light and fluffy.
Remove a small part of the cream. Squeeze the gelatine well, let it melt while stirring and stir this gelatine cream into the remaining cream. Stir the cream in an ice-cold water bath until cooled down.
Whip the egg whites with salt and sugar (2) until creamy. Whip the whipped cream until half stiff. Loosely mix the snow with the whipped cream and fold into the cooled cream, fold in the champagne (2).
Drain the candied oranges a little and divide evenly among glasses. Fill the champagne mousse into the glasses and leave to cool until serving.
To serve, garnish the mousse with pomegranate seeds and mint as desired.