The Spanish tortilla is, without a doubt, one of the greatest symbols of Spanish cuisine. The tortilla is a recipe with a long tradition. It's a basic dish that can be served as a tapa or as the main course at dinner, made with elementary ingredients, and so simple in appearance.
Peel the potatoes and cut them into thin slices of ⅛in (15mm). Dry the potato slices with a clean tea towel.
Peel and slice the onion.
Put a large non-stick frying pan (30cm/12in) on low heat. Cook the potatoes slices on medium heat for about 10 minutes, stirring occasionally to make sure they fry evenly. Then, add the onion slices and continue cooking for another 10 minutes.
Once cooked, transfer to a stainer to drain the excess oil and let it sit for 5-10 minutes.
Crack the eggs into a mixing bowl, season with salt and black pepper, then whisk together with a fork.
Pour the eggs mixture into the potatoes and mix gently.
To a small frying pan add 2-3 tablespoons of olive oil. When the oil starts to smoke, pour the mixture, wait about 20-30 seconds and move the pan so that the tortilla does not stick. Then, lower the heat and, with the help of a slotted spoon, set the edges to make the tortilla more aesthetic. After 2-4 minutes turn and repeat the operation.
Turn off the heat and turn out the tortilla onto a serving board, then cut into 4 parts, garnish with parsley and serve hot or cold.