Chop the couverture and melt it in a bowl over a warm water bath, then let it cool down. Whip the cream until stiff and chill. Separate the eggs. Whip the egg yolks and 1 tablespoon of sugar over a warm water bath for 2-4 minutes (must not be too hot; gives a thick, light consistency). Remove the egg-sugar mixture from the water bath.
Stir the chocolate coating and whipped cream alternately into the foamy egg mixture and allow to cool to body temperature. Beat the egg whites until stiff, adding 1 tablespoon of sugar. Fold in the beaten egg whites and chill for at least 3 hours. Peel oranges so that the white skin is completely removed, then cut into thin slices. Marinate orange slices with liqueur. Caramelise 2 tablespoons of sugar in a pan until golden brown. Remove the pan from the heat and let it cool down until the caramel is slightly thick. Run the caramel in thin strips with a tablespoon onto a piece of baking paper. Let the caramel cool down and store it in a dry cool place (caution: it quickly draws moisture).
Marinate orange slices with liqueur. Caramelise 2 tablespoons of sugar in a pan until golden brown. Remove the pan from the heat and let it cool down until the caramel is slightly thick. Run the caramel in thin strips with a tablespoon onto a piece of baking paper. Let the caramel cool down and store it in a dry cool place (caution: it quickly draws moisture). Arrange the mousse in glasses, decorate with orange filets and caramel grid