The famous spicy fermented cheese of Mykonos, made on the island for over 300 years and designated PDO (ΠΟΠ) for its unique taste and aging. The cheese, made from cow's or sheep's milk, is boiled with pectin until thick, similar to a watery yogurt, then strained in cheese cloth to make a soft whey cheese called τυροβόλια (tyrobolia).
To make the tyrobolia into kopanisti, spicy red peppers and salt are added, along with a 'starter' from an old batch of kopanisti, and the cheese is constantly kneaded for a week while the yeasty fungus does it stuff, then stored in earthenware containers. It's very popular as a meze called mostra, served on rusks with tomatoes and olive oil.
Kopanisti is also made on Tinos and Syros; a similar cheese made on the Aegean coast of Turkey is called kopanisti peyniri or acı peynir.
Image by C messier, Creative Commons License