Potato Omelet (Tortilla de Patata)

Ingredients

• 2 medium potatos (not too small, not too big)
• 5 large eggs
• 1 onion
• salt
• vegetable oil

Hardware

• 1 pan
• 2 dishes with a diameter larger than the pan (very important)

Cooking

1. Peal the potatos, cut them in thick slices (about 1 cm)
2. Boil the potatos in water until they are soft (can cut them with a fork), but not too soft. This takes about 10 mins.
3. While the potatos cook, slice the onion and fry it in oil until it is slightly brown. This takes more than 10 mins, so watch the potatos.
4. Beat 4 eggs and put them with the onion on one of the plates.
5. When the potatos are boiled, take the water away and fry them briefly with oil on the pan to give them just a little bit of color. This can take forever, so make sure you put as many slices of potato in the pan as you can. I can normally fry all the potato in two batches.
6. Mix the potatos with the eggs and the onion in the plate. Mash slightly the potatos with a fork to mix them with the egg, but not thoroughly, you still want to have big chunks of potatos in the mixture.
7. Decision time: do you need a fifth egg?
   For normal size potatos and normal size eggs, add another egg (a total of 5). I use only 4 eggs when the eggs are *extra* large. Also, if it's the potatos that are extra large, you might even need to add a 6th egg.
   The first time I suggest you go with the 5 eggs / 2 regular-sized potatos and see what happens.
   If once cooked, the tortilla falls to pieces then it means you needed more egg (the egg is what holds the potato together). On the other hand, if you see places in the tortilla where there is not potato (just cooked egg), then it means you needed less egg. Unfortunately it will be too late to fix it, but then it will help for the next time.
8. Add salt. Check taste.
9. Put a small amount of oil in the pan, and make sure all the surface of the pan is wet with the oil (not only the bottom, also the sides). Then add the mix. Cook for 5-10 minutes in medium heat until the bottom of the tortilla is yellow with brown patches. At this point the bottom half of the tortilla should be well cooked. If it is cooked almost all the way to the top, that's OK too, just reduce the cooking time for the other side in the next step.
10. Now the tricky part: you have to flip the tortilla in order to cook the other side. To do this, cover the pan with a plate, hold the plate FIRMLY against the pan, then turn the thing over. The tortilla is now upside down on the plate (the cooked side to the top).
    Add a little oil again to the pan and wet all the surface again (this is very important). Then carefully slide the tortilla into the pan. Wait a few minutes until the bottom side is cooked (again until brown patches appear). This usually takes less time than the first side.