Head to Vunkerl Inlet (S). You're looking for a ??? on the north side of the bridge in (H-6). Examine the ??? for a cutcene. You will receive the Vunkerl Herb Memo at the end of this cutscene.
The quest will now appear in your log.
Acquire the Vunkerl Herb by examining the Leafy Patch on the shore of the lake (Ludiwa Spring) in (F-5).
You need to get the proper herb color according to the time of day that you arrive at the Leafy Patch.
If 00:00~07:59 pick red.
If 08:00~15:59 pick blue.
If 16:00~23:59 pick green.
(note - You choose the color of the herb you wish to pick when you pick it, so you do not need to wait until a specific time...just pick the herb that corresponds to the current time.)
It does not matter when you hand in the herb, as long as it was harvested at the proper time.
If you pick the wrong herb you must go back to the ??? at (F-5) and pick a new herb.
After you get the herb, return to the ??? at (H-6) for the final cutscene and the reward of a Carbon Fishing Rod.