Goishi-cha looks like black stones and very different from general leaf tea. Especially its manufacturing process is quite unique.
Goishi-cha is categorized as after-fermented tea in the same way as Awa-Bancha but their fermentation processes are different.
While Awa-Bancha is fermented by lactic bacteria, Goishi-cha has 2 steps of fermentation by molding and pickling.
This process makes it a nice and sour black tea. Goishi-cha of Otoyo has been approved to use a “Original & Genuine” label and is popular as a healthy tea.
When you drink it, steam the lump of tea leaves in the hot water about 5 min or leave it in the boiling water until its tea essence is extracted.