Recommendations for a Sunday dinner in or around Carcassone in late September. Two vegetarians in group who will eat fish and poultry. Others will eat anything!
The restaurant (not the bistro) at Domaine d'Auriac is open on Sunday (through Oct 2nd). It's not inexpensive but the menu seems to cover your requirements and should make for a special evening.
Castelnaudary is not far from Carcassonne and is noted for its cassoulet. Sunday lunch would be a good idea. Restaurant le Tirou on avenue Monseigneur Delangle is just off the A61 highway at Castelnaudary exit and offers a very good cassoulet.
We ate at a restaurant in the middle of Carcassone on American Thanksgiving in 2012 and had a surprisingly pleasant meal. I wish to heck I remembered the name of the place, but I can tell you that it was pretty much in the center, and it was the nicest looking of various places. I had duck breast and thoroughly enjoyed it. One of us had some sort of curried seafood as a starter that was also very good. I expected very little, given that we were in the center of such a touristy place, and have to say that they exceeded my expectations by quite a bit.