1. Peel potatoes and slice them thinly, fry them on some olive oil ina good non-stick frying pan.
2. Add thinly sliced onion, brown them slightly, reduce the heat and put the lid on. Cook until slightly soft.
3. Beat the eggs in a bowl, add salt and pepper and the potatoes and onion. Mix it well so it's well covered and pour it to a hot frying pan with a few teaspoons of olive oil. Reduce the heat, put the lid on and cook for about 6 minutes.
4. To turn the tortilla you can use a large plate, a lid or even a slice. Once turned cook for another 4 minutes withoout the lid on. Cooking times can be adjusted to taste.