PREPARATION

Peel and cut the potatoes and onions in fine strips. In a frying pan, heat oil over a low heat. When the oil is hot, brown the potatoes and onions. During this time, in a salad bowl, season the eggs with salt, then beat them as in omelette. When the potatoes and onions are cooked and brown, remove from the heat and drain with a sieve. Add the potatoes and onions in the eggs and mix.
Heat 1 teaspoon of oil in the frying pan and grease (spread) it with a paper towel, then pour the mixture of eggs, potatoes, onions and leave to cook at a high heat. Once the edges are cooked, place a plate slightly inferior in diameter to that of the tortilla frying pan. Press one hand on the back of the plate and with the other, the handle of the pan to turn over the tortilla. Repeat the movement several time to verify the cooking.
If you wish, you can dress your tortilla with peppers, small pieces of ham, chorizo… Add  these ingredients then in the beaten eggs at the same time as the potatoes.