It takes place in a prehistoric era. The man is sick to death of the meat he's been eating and he discovers that adding something (onions, garlic, or salt - I can't remember) makes it appetizing again. He compares the meat which "fills the stomach but not the mouth" and the additive which "fills the mouth but not the stomach'.
I read it in a sci-fi anthology probably in the 60s or 70s. It was a fantasy, tonally like Clan of the Cave Bear
This is The First by Anthony Boucher.
Sko’s stomach was full but his mouth still felt empty. There had once been a time when his stomach was empty and his mouth felt too full. He tried to remember. And then, as his tongue touched around his mouth trying for that feeling, the thought came.
...
He pulled the hard purple-brown skin off one yellow-white section and smelled it. Even the smell filled the mouth a little. He blew hard on the coals, and when the fire rose and the stewpot began to bubble, he dropped the section in with the sheep-meat. If one fills the stomach and not the mouth, the other the mouth and not the stomach, perhaps together ...
