No culinary dilemma has been more heatedly debated, not even whether a morcilla de burgos can be considered superior to a morcilla de leon, or which region boasts the best jamón.
So we asked The Local readers to decide and the vote was an overwhelmingly in favour of WITH ONIONS.
A poll of our readers on Facebook revealed 83 percent would choose a tortilla de patatas con cebolla.
While on Twitter, a poll revealed a more balanced split but still most definitely for onions.
Daily dilemmas of living in Spain: It's time to take sides on this historic and bitter debate about whether Spanish tortilla is better with OR without onions. Vote now and let's resolve this once and for all
— The Local Spain (@TheLocalSpain) July 25, 2019
The only question now is, runny or firm?