Peel the potatoes and cut them into cubes. Soak them in cold water for 10 minutes. Heat sunflower oil in a skillet. Drain the potatoes well and carefully add them to the hot oil. Remove the potatoes and drain excess oil using paper towels.

Add a little extra virgin olive oil to a skillet and add the potatoes. (If you want to include onion, sauté it at this point before adding the potatoes.) Beat the eggs and pour them in. Keep the heat low, stir so the egg coats all the potatoes, and cook until the edges are set. Flip the omelette to cook the other side. For a well-done omelette, keep the heat low; for a softer center, increase the heat.

Increase the heat, but not to maximum. Serve and enjoy!