01 -
Pour olive oil into a medium-sized nonstick pan (about 30cm/12 inches) over heat. Toss in potato chunks and cook until golden, tender, and crispy. Add onion, cooking till soft and see-through. Remove and drain all the oil.
02 -
Put potatoes with onions back in the pan, spreading them evenly into one flat layer. Turn the heat down to low.
03 -
Whisk eggs, sprinkle with salt and pepper, and then pour over the cooked potatoes and onion. Stir everything gently with a plastic spatula to spread the eggs evenly across the bottom.
04 -
When the bottom is firm but the top is still a bit wet, grab a big plate and cover the pan. Hold it tightly and flip the tortilla onto the plate. Slide it back into the pan to cook the other side carefully.
05 -
Keep cooking, shaking the pan lightly now and then, until the tortilla is cooked through fully.
06 -
Place a clean plate over the finished tortilla, flip it out of the pan again. Sprinkle parsley on top if you'd like. Serve in small cuts, warm or chilled.