Tar?

I asked this question a while back and below is the answer I got from a manufacturer.

Originally Posted by http://www.StogieReview.com

“This grotesque syrup is somewhat of an enigma. We assume that it is sap left inside the stem of the leaf which doesn’t evaporate during fermentation. It is extremely rare, but by far one of the most pungent and foul substances of the world. It has been my experience that cutting below the ooze usually ends the matter.”

Remainder of that article can be found here