Drain the apricots and collect the juice. Puree the apricots, except for 4 halves. Mix yoghurt, 3 tablespoons sugar and 4 tablespoons lemon juice. Stir in the apricot puree.
Whip cream and vanilla sugar until stiff and fold into the yoghurt mixture. Pour the yoghurt mixture into dessert glasses or bowls and freeze in the freezer for about 5 hours, preferably over night.
Fill up the apricot juice to 1/2 litre with water, take 6 tablespoons of it and mix it with the sauce powder until smooth. Bring the rest of the juice and 2 tablespoons of sugar to the boil, remove from heat and stir in the sauce powder.
Bring the sauce to the boil while stirring and simmer for at least 1 minute. Finely dice the remaining apricots and fold in. Season apricot sauce with the rest of the lemon juice and let it cool down. Take yoghurt ice cream out of the freezer about 20 minutes before serving and let it thaw a little.
Serve with apricot sauce.