Enlighten
If you can find the door in winter shaped like a mouth it will enlighten you.
Imagine searching for this special door in the cold wind and snow of winter. The search for enlightenment always has something to do with suffering and searching on your own like this.
けい
さと, ひら
None
The door enlightened you by opening up and revealing the cake (けい) in its door-mouth. "Cake is the key to enlightenment, my child. Now eat it from my mouth."
All you need to do to attain enlightenment is to eat this cake... out of this mouth. Eh. Maybe enlightenment isn't worth it.