This quest is not available in game.
Bring the Lost Thunderbrew Recipe to Ragnar Thunderbrew in Kharanos.
The Dark Iron dwarves, led by the villain Hurley Blackbreath, stole one of the Thunderbrew's best recipes, Thunderbrew Lager. The villains! They don't deserve such a fine brew!
<name>, I have a tough task for you. Go to the Blackrock Depths in the Burning Steppes, destroy any kegs of Thunderbrew Lager you find, and bring back our recipe for Thunderbrew Lager!
Please, get that recipe back, even if you have to turn Blackrock Depths upside down to do it!