Chimaerok Tenderloin

Chimaerok Tenderloin is an exclusive type of meat previously found on "chimaeroks", a type of powerful chimaera which at one point lived on the Isle of Dread in Feralas. The meat was used in the Scepter of the Shifting Sands questline, both as a quest-objective and as an ingredient for a recipe also given by completing one of the quests.

Source
This item drops from Prince Lakma in Feralas.

It formerly dropped from the following creatures, before Cataclysm:
 * Arcane Chimaerok
 * Chimaerok
 * Lord Lakmaeran
 * Chimaerok Devourer

As a quest objective

 * This item was an objective of The Isle of Dread!.

Cooking

 * Dirge's Kickin' Chimaerok Chops (Cooking)

Cataclysm
In Cataclysm the Isle of Dread has been destroyed by Deathwing, removing, for a time, the only source of chimaerok tenderloins. The questline has also been removed. In Patch 4.3.0 Prince Lakma was added as a new source for the tenderloins.