Put the sugar and vanilla sugar in the mixing bowl and pulverize for 10 seconds / speed 10. Add the frozen fruits and the lemon juice and chop for 15-20 seconds / speed 8. Add yoghurt and process to a cream ice cream for 30 seconds / speed 4 and serve immediately.
You can also put it in a Tupperware container in the freezer for 1 hour, then it is even easier to shape it into balls with the ice cream scoop!