Balute was the worst way to preserve them that I’ve read about. Take a fertilized chicken or duck egg and in 17 days kill it, then bury in the ground for months to ferment. And they call that a delicacy! Pretty gross, and I gotta ask, how in the heck did someone find out that wouldn’t kill you to eat it....
Saw something like this on an Anthony Bourdain show. It was in Vietnam. Coated the duck in some type clay and then buried it. I could never eat it.