Anchovy

Anchovies were a salty food item found on Earth.

To battle the effects of cyanide, the Tenth Doctor needed, among other things, something salty. Rejecting salt as too salty, the Doctor wolfed down a jar of anchovies given to him by Agatha Christie. (TV: The Unicorn and the Wasp)

While having dinner with her former companion Tom, Iris Wildthyme picked the anchovies off her pizza. (AUDIO: Wildthyme at Large)