Meet Germany's most popular mustard: Bautz'ner Senf.

Well, to be precise it's really East Germany's most popular mustard but as it is THAT popular in the East it's overtaking all of the other mustards nationwide. Bautzen (a lovely hill-top town in eastern Saxony) has a tradition of mustard making which goes back to 1866.
Bautz'ner mustard is one of the most popular 'Ostprodukte' (East Products), products that were produced in the former DDR (GDR).