Potliz is in fact a ceramics studio ("pot" as in "pottery", see?), established by someone named Liz Albrecht (yes, it all makes sense now!).
The team of artists working at Potliz produce some awesome work, and now that I know that "Pot Liz" is not a woman selling herbs of dubious origin and intent, I shall make an effort to visit the studio and invest in some of their merchandise. The colours and designs are really beautiful, and the prices look pretty good too.
Apart from anything else, I think they're to be commended for making such original use of a hole in the wall. :-)