It isn't what it sounds like. Rather, we've taken on the persona to disguise the fact that we are attempting to help a number of villages within the fire tribe.
[Kija was sort of offended at first, but it worked. And the important thing was helping them.]
But it's to learn what they are doing differently in the Kai Empire to feed their citizens and what crops it is they go. Yoon said that if it is something that can be cultivated within the Fire Tribe, it might save many lives.