Spanish Omelette (Tortilla de patatas)

1/4 kg potatoes
6 eggs
1dl oil
1 onion

Peel the potatoes, wash them thoroughly and cut them into thin slices. Chop the onion. Heat oil in a frying pan and then add the onion. Sautée the onion until it is brown and then add the potatoes and a little salt. Stir the contents until the potatoes are done. Beat the eggs, add a pinch of salt and then the potatoes. Mix well. Turn the heart up under the frying pan and add the egg and potato mixture. Brown on one side and then turn the omelet over to brown it on the other side.