Tears of Kingdom features many side quests including Incomplete Stable in which players will help NPC do several tasks.
Here, you will help NPC Karson mend the roof of the stable in Lookout Landing. Completing this side quest will unlock and use the mini stable in the region where you can board, register and bring out horses.
How to start The Incomplete Stable in Zelda: TotK
To start the Incomplete Stable side quest, make your way to the Hyrule Field in Lookout Landing in Tears of the Kingdom.
After getting there, you need to find and talk to the Karson. He will be located on the south side of the Lookout Landing near the main gate.
Once you have successfully started the conversation with the Karson, the Incomplete Stable side quest will begin. If, however, you are having trouble talking to the NPC Karson, you might not have completed Hebra which is part of the Regional Phenomena questline.
How to complete Incomplete Stable in Zelda: TotK
All you have to do here is help Karson fix his stable roof. It is an easy objective that will complete “Incomplete Stable” in Tears of the Kingdom.
First, you need to get your hands on the small plank which is located on the right-hand side of the stable. Now, you need to pick the plank using the Ultrahand Ability.
After picking up the plank, what you need to do is find a way to the top of the roof. For that, travel to the back of the stable where haystacks are placed. Use these haystacks as stairs to jump over to the roof.
Once you are on top of the stable roof, you will easily locate the gap where the plank needs to go. As the plank is not perfectly square therefore rotate it to fit perfectly inside the gap.
Once the planks are in line with the gap of the stable roof, place them down where they will become part of the roof. Doing so will complete the Incomplete Stable side quest.
After finishing the repair, you will unlock the mini stable in Lookout Landing by talking to Lester and Karson.