The humble Spanish omelet can be made with chorizo, peppers and onions, among other ingredients, but purists will tell you it should only contain potatoes and eggs.
The potatoes are diced and lightly fried before being added to the egg mixture and fried on a high heat; the trickiest part is when you have to flip the pan over to turn the tortilla.
If you get it right, someone should shout "Olé!;" get it wrong and you'll have gooey half-cooked tortilla everywhere.
Where to try? Any self-respecting tapas bar