Tortilla Espanola

Tortilla espanola is potato and egg, sometimes onion, cooked slowly in a generous amount of olive oil until the potato is soft rather than fried crisp, then set in a pan and flipped. That is the whole recipe, and everything about it is contested: onion or not, which divides the country into cebollistas and sincebollistas; how set the centre should be, with the current fashion for a barely cooked, almost liquid interior arriving from the Basque country and San Sebastian in particular; how thick; and how long the potato is cooked. It is served as a wedge with bread at any hour, as a bar pincho, in a sandwich, or whole for a family meal, and it is one of the few things eaten everywhere in Spain in the same form.

What you actually see

• The onion question - the national division between con and sin cebolla.
• The runny centre - the modern preference for an underset interior.
• The pincho wedge - served on bread as a bar snack.
• The slow potato - cooked soft in oil rather than fried crisp.

When to go

Year-round and at any hour; bars serve it from breakfast to late. Freshly made tortilla in the morning is better than the same one at eight in the evening, which is worth knowing.

Honest expectations

Bar tortilla is often hours old and reheated or served cold, which is normal but not the best version. The very runny style now common in fashionable places is undercooked egg, with the usual caveats. Quality varies more than almost any other Spanish dish.

Nearby

Every bar in Spain; Betanzos in Galicia and the Basque country are known for particular styles.