This page explains how to complete the level 80 post-Shadowbringers quest "Food for the Soul".
This quest is available if you have completed the quest Fraying Threads.
Starting the Quest
Talk to Tataru in the Rising Stones in Mor Dhona to begin the quest.
Speak with Tataru
Go outside and go north to where the orange arrow is pointing in the minimap. Go to the upper level and through the door in the north end of the hallway. Talk to Tataru to proceed. There will be a cutscene.
Deliver the Archon Loaf
You can either teleport to the Crystarium and use the Aetheryte to go to the Dossal Gate, then go east up the stairs and talk to the Crystarium Gatekeep to enter the Ocular, or you can go southeast and talk to the Saint Coinach Ferryman at the gate icon on the map, then talk to the Ironworks Technologist to go to the First. Talk to the Crystal Exarch to hand over the Archon Loaf. There will be a cutscene.
Speak with Urianger
Talk to Urianger to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Thancred to accept the next quest: Faded Memories. There will be a cutscene.