Tasseography is a fortune telling method reading the residue of a liquid drink. The residue leaves shapes or patterns that can be read in a psychic reading. This may be tea leaves, coffee grounds or even wine sediments.
There is speculation about the history of tesseography, probably because it occurred in different places in different ways. There were wax and lead readings in medieval Europe. It also appeared to be performed by the wise women in villages. Coffee readings are more likely to have been performed in the Middle East and Turkey. Tea drinking is different in different countries and tea bags are often used.
On a personal note, I once had a tea leaf reading and I found it very strange. It was very brief and nothing resonated with me, at the time nor later. If I was to use tasseography as a psychic tool, I would tune into the energy of the residue in the cup that I was reading.