First, peel the 3 potato and then cut them in half, then into even quarters. Slice the potatoes so that they are 1cm thick.
Then, put a frying pan on the stove at a low heat. Add a generous serve of extra virgin olive oil and leave to warm up. Once the extra virgin olive oil is nice and warm, add the slice 3 potato in and leave to simmer for up to 5 minutes.
While the potatoes are simmering, peel the 1 onion and slice it into thin strips then add these to the pan once the 5 minutes have passed. Leave the potato and onion to cook through until they start to soften 15 minutes. Once it is done, drain the oil and let it cool down in a mixing bowl.
In a separate mixing bowl, whisk 5 eggs really well. Add 1 tsp. salt and ½ tsp. freshly ground black pepper. Adjust to preference.
Then, proceed to pour the egg mixture into the potatoes and onion. Carefully move the mixture around using a spatula so that the egg gets through and let it rest for 10 minutes.
Pour the mixture into the pan and let it cook for about 10 minutes. Gently stir the mixture occasionally and use a spatula to loosen the edges of the omelette from the sides of the pan. Slide the spatula around the entire tortilla to prevent it from sticking.
Place a large, flat plate over the top of the frying pan. With one hand on the plate and the other holding the pan, carefully flip the pan so that the Spanish omelette turns out onto the plate. Then, slide the uncooked side of the omelette back into the pan and cook for an additional 10 minutes.
The Serving
Finally, serve the Spanish Omelette warm or at room temperature, sliced into triangular or rectangular pieces, garnished with fresh herbs like parsley or chives, and accompanied by a side of aioli, salsa, or bread for dipping.