Spanish Breakfast Tortilla Española (Potato Omelette)

Heat the olive oil in a large frying pan over medium heat. Add the sliced potatoes and onions. Cook gently, stirring occasionally, until the potatoes are very tender and slightly browned, about 20-25 minutes. The goal is to confit the potatoes, not to fry them until crispy. Season with salt and pepper.

While the potatoes are cooking, crack the eggs into a large bowl and whisk well. Season with salt and pepper.

Once the potatoes and onions are cooked, remove them from the pan with a slotted spoon and drain well, removing as much oil as possible. Add the drained potatoes and onions to the whisked eggs.

Return a tablespoon or two of the cooking oil to the frying pan. Heat over medium heat. Pour the egg and potato mixture into the pan. Cook for 5-7 minutes, or until the bottom is set and golden brown. Gently move the pan to prevent sticking.

Place a large plate or lid on top of the frying pan. Carefully flip the tortilla onto the plate or lid. Slide the tortilla back into the pan, cooked side up. Cook for another 5-7 minutes, or until the other side is set and golden brown. The inside should still be slightly soft.

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