It's been a few years, so I can't recommend exact places, but look for trucks.
The trucks are smaller there, and so are the truckers, and so are the cafes, but the old adage holds true: truckers know the best lunch stops.
In my brief experience, Eze and Monaco were a little prescious and overpriced, though beautiful to see. We had wonderful meals in Antibes, Cap Ferrat, Beaulieu, and other smaller towns. And the marketplace in Nice is wonderful.