No! Sacrilege. The recipe that I use, which I reckon is just about perfect
1 x coarsely sliced red onions.
2 x medium potatoes, peeled and sliced thinly
Lots of olive oil - about two cups. Ingredients need to swim in it. You can reuse it, the Spanish do.
6 eggs, at room temperature and beaten in a bowl (size big enough to add other ingredients - see method) with a pinch of salt.
Pour the olive oil into a non-stick pan. Heat gently until moderate - not too hot. Add the onion and cook until transparent but not yet coloured. Add the potatoes and simmer gently in the oil until almost done. Time? - depends a bit on the potatoes and how thin they are sliced - for me about 15 minutes. With a slotted spoon, remove the almost cooked potatoes and onions and add them to the bowl in which you have the beaten eggs. Let it sit for about five minutes, so that the hot potatoes meld with and partially cook the egg.
Tip the olive oil out of the pan, turn up the heat to medium hot, then add the egg mixture to the hot pan. Cook until you think the bottom half is set and lightly browned - should be about 5 minutes (you can test by sliding a spatula carefully under and peeking). Slide the cooked mixture out of the pan into a plate (larger than the pan). Turn the empty pan upside down onto the plate, and flip the pan and plate, so the mixture drops upside down into the pan. Cook the other side.
Yum!