Authentic Tortilla Española

Peel the potatoes and onion. Slice the onion thinly and dice the potatoes into roughly 1/4-inch cubes.

In a large skillet, heat the olive oil over medium heat. Add the onions and potatoes. Cook slowly, stirring occasionally, until the potatoes are very tender and the onions are translucent and softened, about 20-25 minutes. The potatoes should be cooked through but not browned.

Remove the potatoes and onions from the skillet with a slotted spoon and drain well, reserving the olive oil.

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

Add the drained potatoes and onions to the bowl with the eggs. Mix well and let the mixture sit for about 5-10 minutes to allow the potatoes to absorb some of the egg.

Wipe out the skillet, leaving a thin coating of the reserved olive oil. Heat the skillet over medium-low heat.

Pour the potato and egg mixture into the skillet. Cook slowly, using a spatula to gently shape the edges and prevent sticking. Cook for about 8-10 minutes, or until the bottom is set and lightly golden.

Place a large plate over the skillet and carefully flip the tortilla onto the plate. Add a bit more olive oil to the pan if needed.

Slide the tortilla back into the skillet, uncooked side down. Cook for another 5-7 minutes, or until the second side is set and lightly golden. The center should still be slightly soft.

Slide the tortilla onto a serving plate. Let it cool slightly before slicing into wedges and serving. Serve warm or at room temperature.