I've been watching a bunch of Youtube by a guy named Bertram. In one of them he shows himself cutting something, maybe a lump of pitch/sap/something from what I think is a Birch tree. He doesn't explain anything. Then he put the lump in boiling water and wound up with a coffee coloured drink. It looked like he saved the lump for future use. I searched for birch tea and just found steeping twigs and buds. Any idea what he was doing. I can't give you a link because I can't find the vid again.