I love Spanish tortillas. They are a staple food in Spain, great for merienda, (snacks) or even light dinners. The Spanish use the word tortilla to mean any omelet. The typical Spanish tortilla, or tortilla de patata, has potatoes, eggs and onions. Onions are the secret to keeping your tortilla moist and delicious. But there’s a lot of versatility–you can add peppers, other vegetables, take out the potatoes and put in cod fish (tortilla de bacalao) or tuna. On my last trip to Spain I watched one of my friends cook the tortilla with finely shredded carrots instead of onions and it was delicious! So, learn the basics and then let your imagination go. It takes just under an hour to make a tortilla with 6 generous or 8 “tapa” sized portions. These instructions are for a skillet whose base has a diameter of 8 inches.
Ingredients:
about 5 medium sized potatoes,
1 large onion,
6 eggs
and ½ tsp salt.
The ratio of onion to potato should be about 1:3. I like to fry the potatoes in canola oil.
1. Peel the potatoes and rinse them, then dry them. You don’t want them wet so they don’t splash the oil Cut into little pieces, breaking them as you cut them so the pieces will be uneven.
2.To measure the amount of potatoes you’ll need for your particular skillet, place the pieces of potato in the dry skillet. They should take up most of the space, though they will still be loosely piled on one another. Here is a top view of the skillet with the raw potatoes.
3.Cut the onion in half, and then into very thin slices. Turn the cutting board and cut the onion into small cubes.
4.Fill the pan just under ½ way with canola oil and heat over medium high heat.
5.Sprinkle about 1/3 teaspoon salt all over the potatoes, and then place one piece of potato in the heated oil. When it starts to “dance” around and bubble, the oil is ready. Listen to the oil—if it sounds like it is “humming” with the potato, that’s good. If it splatters and makes loud noises, it is too hot and you’ll need to shut off the heat and allow the oil to cool a bit before adding the rest of the potatoes. At the 9:30 position in this picture is a piece that I placed in the center of the pan, but which danced over to the edge when it was ready.
6.Gently slide the potatoes from your bowl into the oil, being careful not to splash. The pan will be very full. Once the potatoes are in place and gently sizzling, add the chopped onions on top. The onions will not be submerged in the oil. An overhead view and I side view are shown below, on the left.
7.If you have placed too much oil in the pan and it is dripping out, you can gently and carefully remove some oil using a table spoon. (See picture on the right. In any case, it’s normal for the bubbling oil to be right at the top edge of the pan. Cook like this for about 6-7 min.
8.While you wait, crack 6 eggs into a large bowl where the potatoes were, and beat them thoroughly. The first picture shows incompletely beaten eggs, where you can see transparent gelatinous masses. The second picture is what the eggs should look like. 
9.Once the potatoes have cooked for 6-7 minutes, it’s time to mix them–both to cook the onion and to be sure the bottom potatoes are not burning. Using a fork, gently bring the potatoes from the bottom and edges of the pan, toward the center, folding the onions into the mixture and allowing them to submerge in the oil. You will also notice that the overall volume of the mixture has been reduced now.
10.Continue cooking for about another 7-8 min, gently turning the potatoes with your fork every few minutes, and prodding them to check that they are cooking evenly and thoroughly. This is a very critical step in the process. If the potatoes are undercooked, the tortilla will not taste good. I recommend sampling the largest chunks, maybe 6-8 different ones from different parts of the pan, to be absolutely sure they are all very soft. A good test is to carefully remove a chunk and place it on your cutting board. It should mash very easily with a fork, as shown below on the left..
11.When the potatoes are done, lower the heat and using a slotted spoon or spatula, transfer them little by little to the egg mixture. Be sure to drain as much oil as you can, but don’t take so long that the ones still left in the pan get oil-logged or cook to a crisp. It takes me about 2 minutes to do this, which is fine. 
Don’t worry about mixing the egg yet, and don’t worry that parts of the egg will coagulate, just keep going until you have all the potatoes into the eggs. The onions will resist your efforts, floating on the surface of the oil after you’ve gotten he last potatoes. Patience. Just keep going—you want all those little pieces.
12.Carefully pour the oil all out of the pan into a heat-proof recipient. Then pour about a tablespoon of oil back into the pan and place it to heat over a medium fire.
13. Now, while that heats, take your fork and gently mix the potatoes with the egg, bringing the parts from the edge of the bowl into the center. You don’t want to mash the potatoes, which should be very soft, but you still want to keep discreet pieces as much as possible. It should look like a lumpy mess. When it is mixed and oil is warm, pour the mixture into the pan.
14. Then use your folk to gently mash it down, filling all the crevices of the pan.
15. Keep a close eye on it now. Use your fork to softly prod and pry around all the edges to help make it rounder and to allow you to monitor how much it is cooking underneath. If it’s getting too brown and the eggs are still too raw, lower the heat. Also shake the pan gently every few seconds. 
16. Now comes the tricky part. Remove the pan from the fire, and take it to the sink in case you spill it while maneuvering. Hold the handle tightly and place a large plate firmly over the pan, and then in one steady motion, (it’s more important to be even in your motions and keep the plate tightly pressed against the pan than it is to be quick) you turn the pan/plate sandwich over, transferring the tortilla onto the plate. Some will run off to the side, don’t worry, there’s time to fix that.
17. Now, add a bit of oil (from the oil you just used to fry the potatoes) to the pan and return to a medium-low heat. Then gently slide the tortilla back into the pan. 
18. Cook for a few more minutes, tucking the edges in with a fork to get that nice, round shape. Occasionally test to see how well cooked it is by prying it open a bit in the middle. This will help you to control how done it is—some people like the center “wet”, with the eggs still runny, and others just like it moist. Also continue to shake from time to time. Total cooking time once you’ve turned the tortilla is 5-7 minutes.
And there you are! Enjoy with a nice, crusty bread and some slices of Spanish goat or sheep’s milk cheese and some olives.
