After you've taken down Lord Ahune in the Slave Pens, loot the Ice Chest he drops. If you get an item called Shards of Alune, you can right-click it to start the quest. Um, then the rest is ever so tough. You just trot yourself over to Luma Skymother, a female Tauren in the Slave Pens and complete the quest with her. She'll give you 20 Burning Blossoms and your choice of tabards -- either with Flames or Skies. Note that you need to be at least Level 66 to obtain and complete this quest.
That's all there is to it! Well, except for making it through the Slave Pens alive and defeating Lord Ahune and some junk. But hey, who knows, maybe when you get yours, it will show this elusive mystery tooltip when you inspect it. A prize inside, just like Cracker Jacks!