Soak the gelatine in cold water. Wash the orange hot and finely grate the peel. Mix yoghurt, quark, orange peel and 2-3 tbsp. stevia. Squeeze the gelatine and dissolve carefully. First stir in about 3 tbsp. yoghurt cream, then stir into the rest of the cream.
Cool briefly.
Whip the cream until stiff. As soon as the cream starts to gel, fold in the cream. Smooth the mousse in a flat bowl and chill for at least 4 hours.
Wash, clean and slice the strawberries. Squeeze the orange. Arrange strawberries in a fan shape on six plates and sprinkle with 1 tablespoon of Stevia if necessary. Make cams from the mousse and place them on the strawberries.
Serve with orange juice and pistachios.