OK, now you've got me going crazy. I ate at what I'm certain is the same restaurant 6 years ago. As best I can tell, it's either L'Esplanade in Domme or La Belle Etoile in La Roque-Gageac. Looking at the pictures, I believe we ate at the latter. All I recall was that it was excellent and the setting was magnificent. Either way, websites are below for both.

http://hotel-belle-etoile-dordogne.fr/gb/lieux.htm

http://www.esplanade-perigord.com/