Is Spain's famous potato omelette best with or without onion? The results are in...

It is one of the great debates surrounding Spanish cuisine and its answers divide the country as passionately as a Madrid-Barça football match. No matter how many arguments are given for and against and how many chefs openly take a stand, it is practically impossible to change anyone's mind. Should tortilla de patatas (Spanish omelette) be prepared with or without onions?

Spaniards seem to have definitively resolved this dilemma with a landslide victory for one of the options. The Centro de Investigaciones Sociológicas (CIS) has asked about this issue in its latest study on 'Tourism and Gastronomy' and those who said yes to onion have won the debate.

According to the data published in the September 2025 report, 74.9 percent of those surveyed say that the omelette should be made with onion, compared to 18.9 percent who prefer it without. Of the remainder, 5.8% said that it can be made either way and the remaining 0.4% did not know or did not answer.

The CIS survey delves a little deeper into the ideal way to prepare this national dish: 53.3 percent of those surveyed considered that it should be only lightly cooked and 28.9 percent said that it should be very well done. The option 'just right' was only chosen by 15.5 per cent of those interviewed, which reinforces the idea that everyone has their own idea as to how it should be.

What most people do agree on is that tortilla de patatas is one of the most typical dishes in Spanish cuisine. In fact, they rank it in second place, only behind paella and above Iberian cured ham. 26.8 percent of those surveyed consider it to be the most representative dish and 31.5 percent the second most representative. Behind, but a long way behind, are Andalusian gazpacho, cocido madrileño and croquettes.