Traditionally, Biska is made in Istria from an apple distillate using the right amount of mistletoe leaves that are harvested high in the treetops.
The original recipe comes from the Celts who lived on the Istrian peninsula at the time and is around two thousand years old. Biska is the local name for mistletoe (Latin: Viscum album), whose healing properties were known in ancient times. It was highly valued by the Celtic Druids, Greeks and Romans. (Perhaps feared by the Romans when you think of Miraculix, the druid from "Asterix" ...)