Directions

1. Heat a little of the oil in a large frying pan on medium low.
2. Cook onion, stirring occasionally, until caramelised, about 15-20 minutes.
3. Slice potatoes 5mm thick and wash in a bowl of cold water.
4. Drain well and pat dry on a paper towel.
5. Place potatoes in a large bowl and season with salt, then transfer to a deep frying pan.
6. Pour remaining oil over potatoes and heat on medium.
7. Cook at a gentle boil for 10 minutes, until just softened.
8. Remove potatoes from oil with a slotted spoon and drain well (set oil aside for another use).
9. Whisk eggs in a large bowl, season with salt.
10. Stir in onions and potato.
11. Heat a little of the leftover oil in a 25cm (10 inch) non-stick pan on medium high.
12. Add potato mixture and cook for 1 minute to seal base.
13. Reduce heat to medium low and cook for 10 minutes, until edges are set and middle is still a little wobbly.
14. Run a spatula around edges to loosen, then invert the tortilla onto a large plate and then immediately slide back into the pan.
15. Cook for a further 1 minute.
16. Slide tortilla out of pan onto a serving plate and let cool a little before slicing to serve.