I have to admit it took my a while to catch on to this Spanish staple, the tortilla. Spaniards love this dish. You see it in every bar in Spain and in every household. It seems like they never tire of it (especially my husband). It is a savory egg, potato and onion dish, much like a frittata, and of course they are endless variations possible. My mother-in-law cooked several for us, so I was able to watch and learn her style so I can recreate (and try out my own versions) for my husband at home.
First she cooks chopped onion and slices of russet potato in (lots of) olive oil. Start on med-high heat, then once the onion sweats a little, turn the heat to low and partially cover, cooking them slowly, careful not to let them color.
Once the potatoes are very soft, but not disinergrating, strain the mixture over a bowl for a few minutes, collecting the excess oil (to be used when frying the tortilla).
Beat some eggs in a bowl, stir in the potato mixture, add some salt, and pour into a heated non-stick pan coated with some of the excess olive oil. You may begin the cooking at med-high heat, using a silicone spatula to scrape the sides and stir slightly, then lower to med-low, and let the tortilla sit and cook.
My mother-in-law inverts the tortilla one more time, cooking the first side twice. For this one, I just inverted it once. You want to let it brown a little, but not much. Avoid over cooking the tortilla, making it dry and rubbery. A good one will be moist with a creamy-like texture and mouthfeel. You may play with the ratios – for this one I used 4 eggs, 1/2 onion and one large potato (and a 10 inch non-stick pan). Experiment with more eggs for a taller tortilla, chop the potatoes into cubes instead of slices, and start adding other vegetables. I also make a zucchini and onion tortilla which we love. In Spain they eat this cold or room temp, but I like my eggs warm so I like it fresh from the pan.