Bring 5 Savannah Lion Tusks, 5 Plainstrider Kidneys, and 1 Thunder Lizard Horn to Brewmaster Drohn in Ratchet.
Would you like a taste of Chen's namesake? Ahh, the stormstout is a mighty brew. Chen taught the recipe to my mentor, and my mentor passed it on to me. I'll need you to get me a few things, but I can tell you this: the kick is worth it.
Bring me 5 savannah lion tusks from any savannah lion, 5 plainstrider kidneys from any plainstrider, and 1 thunder lizard horn from any species of thunder lizard. That should do the trick nicely.
You can find these ingredients throughout the Barrens.