Spanish Tortilla (Tortilla de Patatas)

                                                                 
  I grew up eating a fair amount of this wonderful potato and egg dish.  To me, it is the epitome of comfort food.  It brings me back to childhood, it fills my belly, and it is just so darn tasty. In the States, some people say that it's the Spanish version of the frittata.  I don't think about that much, I just know that is is one of the most versatile dishes you can prepare.  It is cheap as heck, it is simple, it is delicious, and you can eat it hot, warm, room temperature or even cold straight out of the fridge.
 It also travels extremely well, so it's a great house warming present, pot luck dish, picnic food, airplane or road trip snack and lunch for work or school.
You can also add as many extras as you want: mushrooms, peppers, kale, carrots, tomatoes, etc.... Any vegetable that is good cooked, will be good in your tortilla.  So any leftovers in the crisper are good bets.  If you happen to have some roots lying around, you can slice them and mix them with the potatoes.  For example, you can make a Celery Root and Potato Tortilla, instead of just potatoes.
  If you want extra protein or flavor, you can add bacon, sausage, or even ground meat or chicken pieces.  However if you are serving it at a party it's best to stick to the basics in case there are any vegetarian guests and just add additional vegetables to make it a little more interesting.

For one basic large tortilla, you will usually need about two Russet potatoes, one onion and six eggs as your base.  In San Francisco, at current Whole Foods Market and/or Farmer's Market prices, using an organic onion, organic potatoes, and pastured eggs, the total amount for these ingredients in dollars is  US$ 7.00.
For one meal, for a group of people who eat as much as I do (for those of you who don't know me, I eat A LOT), you can get at least six servings from these ingredients.  That's lunch for roughly US$ 1.17 a head.  If you eat less than I do, you might be able to feed 7 or 8 people with this dish, and if using as an appetizer or hors d'oeuvre, you can have as many as 20 little pieces from this tortilla.
If you add enough vegetables, you can get a complete meal from it as well.
Needless to say, I really think you should try this! 
The recipe will vary a lot from one family or region to another.  Some people like it soft in the middle, others prefer it well done.  Some add more onion than others and the potato to egg ratio varies as well. Some cube their potatoes, others slice them. The one thing they will all agree on is you need a generous amount of Olive Oil, both for flavor and to prevent your tortilla from sticking to the pan.  You can do whatever works for your taste buds, they are all delicious.  I definitely think that it's at its best when still a bit runny in the center, but for travel, it easier to handle when it's a bit firm.
This recipe, from Michel Roux's book  "eggs", works very well:

 1/3   cup       Extra Virgin Olive Oil
 14     oz        Russet Potatoes, peeled and cubed or sliced about 1/4 inch thick (roughly two large potatoes)                   
   2     ea        Onions, roughly chopped
   1      ea       Garlic Clove, diced
   6      ea       Eggs
                      Salt and Pepper to taste
                      Any veggies you wish to add

I took the liberty of writing the method myself for this blog's purpose instead of posting the one from the book.

Heat half of the oil in a non-stick saute pan or well seasoned cast iron skillet.  When hot, add your onions, and cook over medium heat until translucent.

                                                           
 Add the potatoes, and cook stirring regularly, for about 10 minutes or until soft.  Add your garlic and season to taste.  Make sure that the potatoes are completely done, otherwise they will be raw in your final dish.  Trust me, I have made that mistake. 
  Once the potatoes are fully cooked, transfer them to a plate. 

                                                        
Wipe your skillet with a towel, making sure to remove any stuck bits from it. If adding meat or any other vegetables, cook them now, transfer it to the plate with  the potatoes, and repeat the cleaning step. You can always leave the vegetables a little undercooked, as they will cook further when you add the eggs.

                                                      
  In a bowl, whisk the eggs with a little salt and pepper.

                                               
 Heat the rest of the oil in the skillet over medium high heat.  Here you have two options:  you can either mix the potatoes into the eggs in the bowl, and add everything to the pan, or you can put the potatoes in the pan, and slowly add in the eggs, stirring very gently, to make sure that the egg mixture spreads evenly under, around and over the potatoes.

                                                         
 As soon as  the egg on the sides of the pan looks cooked, turn the heat to low, and cook without stirring for another 2 or 3 minutes.  Run a thin silicon spatula through the sides of the pan, to check that the bottom and sides of the tortilla are indeed cooked, and to detach any parts that might have stuck. 
  Now this is the tricky part, but you must  not be afraid of it.  With a "just do it" attitude, this always works.  Turn the heat off, and place a flat plate upside down on top of the pan.  Hold the plate with one hand, and the pan with the other, and flip the tortilla onto the plate.  If you are using a cast iron skillet, you might want to enlist some help as they can be rather heavy and make this move a little challenging.  Then slide the tortilla back onto the pan, raw side down.  Cook on low heat, for another 2 to 3 minutes.  At this point it is up to you how much you cook it, if you want it runnier, 2 minutes should suffise, if you want it firmer, you might want to go closer to 4.  Touch the center of the tortilla to give you an idea. 
You can always finish it in the oven without the flip, but I think it comes out much prettier when cooked on the stove on both sides.
When done, slide it back onto a clean plate, and you can either eat it right away, or save it for later.

    
 Once you make this a few times, and realize how easy it is, you might become slightly addicted to it.  Keep it interesting adding different vegetables each time, as well as creating different combinations.  For this one I used kale and wild mushrooms.  We had it for dinner one night, lunch a few days later, late snack the other night, and I ate the last of it yesterday as my work lunch.  It was divine.