I’m stumped, then. If a newer version of the game is available you might be able to update it and try searching again.
I don’t know if you are aware of it, but this is a utility that you can use to download updates. It automatically updates the game and puts your save back so there’s nothing you have to do except tell it where the game is.
It won’t bring the acorn meal recipe back, but you can use bird or reptile eggs or cooked dandelion greens in the place of the acorn meal to make meat soup. You can forage the eggs and find the dandelions laying around in fields.