1. Heat the oil in a pan
2. Add the potatoes and the salt; when the oil begins to bubble, reduce the heat and simmer those potatoes for 15 minutes or until you can easily pierce them with a knife.
3. If you want browned onions, add them with the potatoes. If you want tender, transparent onions, add them about halfway through.
4. Remove the potatoes and the onions to a bowl with a slotted spoon.
5. Add the eggs and careful CAREFULLY fold everything together taking care to preserve the integrity of the sliced potatoes. Add mixture back into the hot oil, reducing the temperature to low.
6. Cook the tortilla in the oil until the edges begin to brown slightly and the eggs in the interior are turning solid.. You may have to jostle the potatoes and eggs to make sure the potatoes stay submerged.
7. Flip the tortilla (see below) and continue cooking until the eggs are done.
8. Serve warm.

Flip the tortilla

1. CLASSIC TECHNIQUE:
   1. place a large plate over the pan and, holding it firmly in place with one hand, flip the pan and the plate together so the tortilla is now on the plate. Take a moment to admire your remarkable control and savoir faire.
   2. Slide the tortilla back into the pan to finish cooking.
2. THE TWO-PLATE WAY OF THE COWARD:
   1. slide the tortilla onto one plate.
   2. place the other plate over it. Hold the plates together and flip the tortilla over. It is now on the second plate and upside down. Yay.
   3. Slide it back into the hot pan and continue cooking.