01 -
Warm up olive oil in a medium-sized, nonstick pan (30cm/12-inch size). Cook the potato cubes until they're golden, crispy, and soft inside. Toss in the onion and sauté until it's clear. Pour out the oil entirely.
02 -
Put the potatoes and onions back into the pan. Spread them out in a flat layer and reduce the heat to low.
03 -
Whisk the eggs with some salt and pepper. Pour the mixture over the onion and potato layer. Stir everything gently with a plastic spatula to make sure the eggs start setting evenly at the bottom.
04 -
Once the bottom is solid but the top is still a little wet, cover the pan with a large plate. Hold the plate tightly, flip the tortilla onto it, and carefully slide it back into the pan so it cooks the other side.
05 -
Let it finish cooking, giving the pan a gentle shake every so often. Once it's fully firm all the way through, you're good to go.
06 -
Put another plate on top of the tortilla and flip again to remove it from the pan. Sprinkle parsley over it if you like, slice into squares, and serve however you prefer—warm or cold!