Different parts of Spain are known for different parts of foods, or will even cook the same dishes differently. For example, tortillas (Spanish omlettes) are cooked differently based on the region.
I tried a tortilla, which is a spanish omlette.
It is typically served with bread and it was amazing! I wanted more!
The three main ingredients are eggs, potatoes, and olive oil - onions are really common to add. In Galicia, tortillas usally have a soft or gooey center, while other regions have a more solid interior.
Yes, most restaurants typically use locally-sourced products. Olive oil is produced throughout Spain, although less common in Galicia. However in Southern Spain it is very common.