La socca is a kind of a pancake made with chickpea flour. It is cooked on large dishes in ovens and must be eaten fairly quickly, while it's hot. The cook will cut small pieces for you, which you'll be able to take away in paper bags or eat on a plate in the shop.
You eat it alone or rather with pepper. You'll always find some self service pepper in a real socca place.
It's a typical local specialty.