Ingredients
Two large baking potatoes (or the equivalent amount of other potatoes)
One small yellow onion, or half a large yellow onion
4 eggs
salt
olive oil
Peel the potatoes (I don't, but I'm lazy) cut each in half lengthwise. Cut each half into slices about 2mm thick. Dice the onions. Mix the potatoes, onions, and 1 - 2 tsp of salt (depending on your taste).
Add about 1-2 Tbsp of olive oil to a frying pan and heat it to medium heat. Add the potatoes and onions and cook, stirring constantly, for 15-20 minutes until the potatoes are soft, a little golden, but not crispy.
When the potatoes are done, beat the 4 eggs lightly in a bowl, and add the potato mixture. Let sit for 5 minutes.
Heat another 1Tbsp of olive oil in a smaller frying pan to medium heat. Add the egg and potato mixture. Flatten this out to get the traditinoal Tortilla shape. Once you feel that the whole thing can be flipped, flip it. I usually put a big plate face down on top of the pan, turn the whole thing over so the tortilla is on the plate, and then slide it back into the pan. Continue cooking on the new side. Flip it about 4 times until the tortilla is a nice golden color.