What Amy Winehouse recording has just her and a basso guitar?

Hi,
I'm not real familiar with all of Amy Winehouse's discography, but I remember hearing a song da her that was just her Canto along with a basso as the music... no horns/guitars/drums.
It was a really great song, but I never found out the name, and I have been unable to find it since.

Do any of te know what song I am thinking of, and do te know where I might be able to find it?

Thank you.