A lovely restaurant in a beautiful old building with a delightful interior design. The location is easily accessible in the Ville Basse (the main part of town), just a few blocks from the pedestrian Rue Georges Clemenceau and the central Place Carnot.
We had the lunch plates (pay by the size of the plate, and they fill it out generously). The price was comparable to many pay-by-weight veggie buffets in European cities, and probably a bit cheaper than them. Every single thing we had was delicious, and a lot of the options were very healthy too. The staff were acutely conscious of vegan/vegetarian differences, and I believe several items were vegan.
Yes, they do serve non-veg food, but they say it's due to lack of choice: it's hard to survive as a pure veg place in Carcassonne. So, cut them some slack, and give them your business. Most food options in Carcassonne are so unappealing and generic that this may well be one of the very best restaurants in town.
The staff are supremely friendly, and one of them speaks excellent English, for those for whom that sort of thing is an issue.
As of this writing (July 2013), they did lunch and dinner every day (including Sunday? not sure) with the sole exception of dinner on Monday.Pros: good buffet, tasty and healthy, lovely location and staff