Mix the yogurt with sugar and the lemon / orange flavor in a container. Squeeze the oranges and add the juice and the pulp of the oranges (possibly puree) to the yogurt mixture. Whip the cream until stiff and stir into the orange yoghurt mixture.
Place in the refrigerator for a while to pre-cool and then put in the ice cream maker. The ice cream is ready after about 30-40 minutes.