Tortilla de patata is both delicious and ubiquitous in Spain. As you can see from the picture below, it is a dish made primarily of potatoes and egg. Among Spaniards, however, you can spark a debate about whether or not to add onion as well (grocery stores offer it premade both with and without cebolla). Honestly, though, you can’t go wrong either way.
![](https://cocina-casera.com/wp-content/uploads/2015/01/receta-tortilla-patatas-facil.jpg)