Cut the peeled potatoes into small pieces. Heat a pan with olive oil and place the potatoes in it. Use moderate heat.
Crush onion and also add it to the potatoes.
Fry it up slightly until it gains a brownish color and after 10 minutes, drain the oil. Salt the mixture and add it to the pre-beaten eggs in a large bowl.
Return the pan to the stove with a little olive oil and add the eggs with potatoes.
Cover the pan with a lid and let it cook for 5-10 minutes, until the bottom becomes brown.
Using the lid, flip the tortilla and fry it until brown on both sides. Place the ready tortilla on a plate and after it cools, serve.