Are restaurants open in roussillon in November?
Yes, maybe not all of them, but at least many of them.
You may find more selection at lunchtime, when there could still be more day-trippers visiting vs. people staying overnight. I found some smaller or lesser-known villages pretty quiet in early November, but I never starved.
Some will be open. I'd be sure to get reservations; ask your lodging to reserve dinner for you. When the towns slow down, less places are open. The ones that are still open can get full.