Thavnairian Onion

Thavnairian Onion is miscellany. It is used as feed to train chocobo companions past rank 10.

Source
Thavnairian Onions can be obtained as a quest reward or grown in a garden from.

Quests
Thavnairian Onions can be obtained as a reward from the following quests:
 * Landing a Stable Job
 * A Hunter's True Nature