This is not a recipe, there are no measurements, but all will become clear if you decide to cook this delicious Spanish snack.
My organic method is; mostly fill a frying pan with chopped raw potato (good chunks, not fine dice or slices) and chopped Spanish onion.
I used 1 large Spanish onion for 4 baking potatoes and that filled my pan within an a few cm of the top.
Pour in olive oil (not extra virgin, one should never cook with EV, it’s a waste!) to just cover the potatoes and onions (yes, COVER), then put on a low heat and cook the potatoes and onions trying not to colour. When tender, remove potatoes and onions from the oil and allow to cool a little in a bowl.
Pour oil into a glass jug to cool (you can use it for other cooking later).
Next; eggs. Whisk 2 at a time and add to cooled potato mix until you have just enough to bind the mixture well. It took 5 for my pan. Add salt and pepper, mix well, then pour back into reheated pan with a little of the oil added, maybe a tablespoonful.
Press mix down and gently cook on a low/medium heat, probably about 15 minutes, you’ll be able to smell when the bottom of the tortilla is browning. At this point there are two methods of finishing, the ‘authentic’ way or non authentic.
Authentic; take pan off heat, let cool for a few minutes then put a plate that fits over the pan upside down on said pan and flip everything over, this leaves the original (uncooked) top of the omelette on the plate and the (cooked) bottom showing.
Add a little more oil to the pan and slide the tortilla back in, pressing down carefully. This gives the authentic shape. Be careful because of oil, uncooked egg etc, use oven gloves and 2 people maybe.
Non-authentic. Stick pan under a medium grill to cook the top!
Best served warm, or cold, not hot.