In your dialect. 
In mine it is "Tasje" (pronounced "Tas-chje", pretty much like the Dutch "tasje", except that this means little bag). Standard German would be "Täßchen" (or with a double ss; pronounced "Täss-chen" with a soft "ch").
@iris I would not know how to say it in Hamburg. People would understand "Täßchen" and "Tässle", though. Of that I'm sure. <smart ass mode: off>