Basilisk blood

"Basilisk's blood. It will give cooked meat a savory smell, but if eaten it produces violent madness, in beasts as well as men. A mouse will attack a lion after a taste of Basilisk's blood."

- Oberyn Martell

Basilisk's blood is a poison. It gives cooked meat a savory smell, but if eaten it causes violent madness, in animals as well as humans.

In the books
In the A Song of Ice and Fire novels, a paste is a paste spiced with basilisk blood to produce Basilisk venom, which gives meat a savory scent but which induces a violent madness in any creature with warm blood, whether man or beast.