What Spanish dish is a thick omelette made with eggs, potatoes, and onions?

What Spanish dish is a thick omelette made with eggs, potatoes, and onions? The answer is tortilla española. Also called tortilla de patatas or Spanish omelette, it is one of Spain’s best-known dishes.

The basic preparation combines sliced or diced potatoes with beaten eggs; onions are often included, though their presence is famously debated in Spain. The potatoes and onions are gently cooked in oil until soft, mixed with the eggs, and slowly cooked into a thick round omelette. It is turned during cooking so both sides set.

Spanish omelette is commonly served warm, at room temperature, or chilled. It appears as a tapa, in wedges, or as a pincho de tortilla. A 1817 Navarrese document contains the earliest known Spanish reference to a potato-and-egg tortilla. A later story credits Carlist General Tomás de Zumalacárregui with inventing it during the 1835 siege of Bilbao, although historians treat that tale as unproven.

It is not the same as a French omelette, which is usually thinner and made primarily from eggs. Nor should it be confused with a Mexican tortilla, which is a flatbread.