The ultimate Spanish comfort and party food, the Spanish tortilla, or tortilla de patatas, is a potato omelet or frittata that can be served as a tapa, side dish, or light meal.
Peel and wash your potatoes and break them into small, somewhat evenly sized pieces.
If you decide to use an onion in your tortilla, peel and chop it.
Add the olive oil to the frying pan and heat on medium heat. Some people add enough to cover the potatoes. Others use less, and stir the potatoes more often to ensure they are fully cooked. When it has warmed up, add the potatoes (and onions) and fry at medium heat, stirring them to keep them from burning and sticking to the bottom of the pan.
Keep cooking and stirring until the potatoes are tender. You should be able to easily pierce them with a fork, but they shouldn't easily fall apart.
Drain the potatoes and onions from the oil. You can use a slotted spoon or a colander to help drain them, or just carefully remove them from the oil with a spatula at an angle.
In a medium to large sized bowl, beat the eggs with the salt. Then add the drained potatoes and onions, gently stirring the mixture to fully cover all of the potatoes. You should have enough eggs to be able to coat all of the potatoes and onions and reach the top layer of them in the bowl. The potatoes shouldn't be drowning in the eggs, though. Add another egg if you feel it's needed.
Lightly grease a clean frying pan and warm it over medium heat. (Choose a pan that would hold all of the mixture to a height of an inch to an inch and a half. Ours was about 25cm/10inches in diameter.) When the pan is warm, add in the potato, onion, and egg mixture cook it over medium heat. Lift up the mixture around the edges to check for doneness. To help fully cook the tortilla, you can stir it gently while it first begins to cook in the pan. Then leave it alone to fully form a cooked layer.
When the eggs start to set, especially at the edges, lift up the edges to make sure that the tortilla isn't stuck to the pan. You can separate the tortilla from the pan by running a fork or spatula around the edges. Move the pan in a brisk, circular motion to check to see if the tortilla has been released from the pan. You are now ready to flip the tortilla.
To flip the tortilla, take a smooth, flat plate that is bigger than the size of your frying pan and place it upside down over the top of the pan. Firmly hold the plate over the pan as you carefully flip the pan over allowing the tortilla to fall onto the plate.
Clean the pan, if any bits have stuck to it. Then, coat it with oil and heat it again. When warm, carefully slide the tortilla into the pan, leaving the uncooked side down in the bottom of the pan.
Cook for a little while later, long enough to finish cooking through to the center of the tortilla. When you are satisfied with the level of doneness, flip it over again, this time onto a serving plate.
Cut the tortilla and serve it! Enjoy!
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Notes
Serving
The Spanish tortilla can be served warm immediately or made ahead and served later. You can serve it warm, cold, or at room temperature.
Most people slice it like a pie or a pizza. At parties, though, it's very common to cut it into small squares and serve it with toothpicks. That makes it the perfect finger food for a buffet-style service.
Which potatoes?
Generally, the best potatoes for a Spanish tortilla are the same ones that work well for frying. You want potatoes that will mostly hold their shape when cooking.I tend to choose all-purpose potatoes. They aren't too starchy or too waxy. That said, choosing a waxy variety is probably a better choice than overly starchy potatoes that are more likely to fall apart when cooking.While I have to admit that I often choose larger potatoes to try to save time when peeling and cutting, medium-sized potatoes are probably a better choice. They tend to be "younger" and less starchy.
The oil
If you're looking for a strong olive oil flavor, choose extra virgin olive oil. If you prefer a more subtle olive flavor, choose a lighter olive oil. It will also cut down on the cost of the dish slightly. ;)
Runny vs. well-cooked
If you are looking to fully cook the tortilla, there are a few ways to do it. First, you'll want to keep the temperature lower to avoid burning it while cooking it longer.While it begins cooking, you can carefully stir the egg and potato mixture with a fork or spatula. That helps exchange the more raw areas in the center and the more cooked areas below.Some people choose to cover the tortilla while it cooks to help keep the heat in and better fully cook the interior.If you use a pan that is oven safe, you can also finish cooking the tortilla in the oven.
Preventing sticking
To keep the tortilla from sticking, it's important to make sure that the pan is completely clean before adding the eggs mixture. The pan should also be pre-warmed and coated with a thin layer of oil before adding the egg mixture. If you add the ingredients too quickly, while the pan is still cool or lukewarm, they are more likely to stick to the pan.Periodically lifting up the edges all the way around the tortilla while it cooks is another way to help ensure the tortilla doesn't stick.