Start by peeling and slicing the potatoes into thin rounds.
In a frying pan, heat a generous amount of olive oil over medium heat.
3 tablespoons Olive Oil
Add the sliced onions to the pan and fry them until they are softened and slightly golden.
1 large Onions
Once the onions are cooked, add the sliced potatoes to the pan and cook them until they are tender and lightly browned.
4 medium Potatoes
While the potatoes and onions are cooking, crack the eggs into a bowl and beat them well. Add a pinch of salt, pepper, and nutmeg to the beaten eggs. You can also add a splash of milk for extra creaminess.
6 large Eggs, 1 teaspoon Salt, 1/2 teaspoon Pepper, 1/2 teaspoon Nutmeg, 2 tablespoons Milk
Once the potatoes are cooked, transfer them and the onions to the bowl with the beaten eggs. Mix everything together until well-combined.
Return the mixture to the frying pan and cook over low heat. Use a spatula to draw the edges of the mixture into the center, allowing the uncooked egg mixture to flow to the edges.
Cook the tortilla until the egg is set but still slightly runny on top.
To finish cooking the tortilla, you have two options: either flip it in the pan and cook the other side, or place it under a hot grill to brown the top.
Once the tortilla is cooked to your liking, remove it from the heat and allow it to cool slightly.
Cut the tortilla into wedges and serve it warm or at room temperature.