This is one of the most popular dishes in Spain. It can be served warm, at room temperature or chilled, and is even better when served with romesco sauce.
Peel the potatoes and slice into 1/4 inch slices. Set aside.
Preheat the oven to 375F. In a (10 inch) ovenproof skillet, heat 1 Tablespoon of the olive oil over medium-high heat. Add the onion and cook until light golden. Transfer to a bowl.
Add another 2 Tablespoons of oil to the pan and place a layer of the potatoes in the pan. Cook the potatoes for about 2 minutes per side (being sure not to brown them). The potatoes should be tender when pierced with a paring knife. Transfer to the bowl with the onion.
Repeat by adding an additional tablespoon of oil and layer of potatoes until all the potatoes are cooked.
In a large bowl, beat the eggs. Add the potatoes and onion to the eggs. Season with salt and freshly cracked pepper.
Heat an additional 2 Tablespoons olive oil in the pan. Add the egg/potato mixture and cook over medium/high heat for about 3-4 minutes. Slide a spatula around the edge of the tortilla to check that the bottom has set.
Place the skillet in the preheated oven and continue to cook for about 20-25 minutes, or until the eggs are set. Remove from the oven and let cool for 5 minutes.
Loosen the edges of the tortilla by running a spatula around the edge of the skillet. Invert onto a plate and cut into wedges or squares and serve with Romesco sauce.Ā
Can be served at room temperature.
