Spanish tortilla, a potato omelet, is a delicious mixture of fried potatoes and fried onions with eggs.
Martha Stewart actually has a very good traditional-style recipe on her site:
http://www.marthastewart.com/tortilla-espanola?autonomy_kw=spanish%20tortilla
My mother-in-law makes it just the way Martha describes, but that requires flipping the tortilla out of the skillet onto a plate, and turning it over to cook the other side. I can't do this. I ALWAYS drop it. So I do it like a frittata in the oven. We made one last night and here are the pictures.
Preheat the oven to 375.
Spray a pyrex pie dish with a little bit of cooking spray.
Chop 1 medium yellow or white onion.
Chop 2 tablespoons fresh parsley.
Peel 2 medium-large russet potatoes and slice into thin rounds.
Heat 1/4 olive oil in a skillet and fry the onions and potatoes, but don't brown them. You will be baking this in the oven for 20 minutes or so, so the potatoes don't have to be 100% ready. After a few minutes, add the chopped parsley. When the potates are soft enough to eat but not yet golden, take them out of the oil with a slotted spoon and place them in the pie dish. Let them cool down for 7-10 minutes or so, so that the eggs don't cook unevenly when you add them to the dish.
Beat 8 eggs together very well, and add a tablespoon or so of cold water. I was very fortunate that Spiderman stopped by at the right time and helped me beat the eggs.
When the eggs are well-beaten and the potatoes and onions are cooled a little, pour the eggs over the top of the potatoes. Now it looks like a frittata.
Bake it in the oven for 20 minutes or so or until the eggs are set. I usually check at about 18 minutes, and sometimes it goes as long as 22. You don't want the eggs to brown too much, but you don't want them runny either. Sometimes there will be olive oil rising to the surface from the potatoes, and that looks like the eggs are runny, but it's just the extra oil, which you can blot with a paper towel.
Enjoy hot, or at room temperature, which is what we like best!