Dalek juice

Dalek juice is a flavourless potable black fluid secreted by a Kaled mutant as its flesh is boiled. When a captured Dalek was in the possession of Nigel Rochester, it was frequently tortured. One of the methods used, electrocution of a magnetic floor, would cause the mutant within the casing to boil and secrete a black fluid. The fluid was then collected by guards and considered a rare delicacy. However, the amount collected was meager and it took months for the Dalek to recover sufficiently to be boiled again.

The Doctor was given a small cup of this liquid to revive him after a fainting fit. He described the liquid as being "rather tasteless." His companion, Evelyn Smythe, found the boiling and collection process to be obscene. (BFA: Jubilee)