Wash the currants and pluck from the stems. Mix with the sugar and mash lightly with a fork.
Pour into a large glass and let stand for about 1 hour.
Halve a vanilla pod and slit lengthways. Put in the glass.
Pour yeast schnapps on top and let stand in a light place for a year.
After a year, strain off the top and then filter. I always do this with a very fine-meshed tea strainer. But you can also let it run through a paper coffee filter.
Remove the vanilla pod, wash it and let it air dry. It can still be used to flavor sugar.