Tortilla espanola de patatas

Peel the potatoes and slice them into thin rounds, approximately 1/8 inch thick, using a sharp knife or mandoline. Pat the sliced potatoes dry with paper towels to remove excess moisture.

Heat the olive oil in a large skillet (preferably 10-12 inches) over medium heat until shimmering but not smoking.

Add the sliced potatoes and onions to the hot oil, stirring occasionally to cook evenly. Cook until the potatoes are tender and beginning to soften, about 15-20 minutes.

While the potatoes cook, crack the eggs into a large bowl and beat them well with a pinch of salt and pepper until fully combined.

When the potatoes and onions are tender, carefully drain them in a colander placed over a bowl to reserve the oil; this oil can be saved for future use.

Pour the beaten eggs over the drained potatoes and onions in the bowl and gently stir to combine, allowing the potatoes to soak up the eggs.

Return 2-3 tablespoons of the reserved olive oil to the same skillet over medium heat, tilting to coat the bottom and sides evenly.

Pour the potato and egg mixture into the hot skillet, spreading it evenly and gently pressing down with a spatula. Cook without stirring until the bottom is set and golden, about 8-10 minutes.

Slide the tortilla onto a large plate, then carefully flip it back into the skillet to cook the other side until set and lightly golden, about 5-7 minutes.

Transfer the finished tortilla to a serving plate and let it rest for 2-3 minutes before slicing. Season with additional salt and pepper to taste, and serve warm or at room temperature.