Tortilla

Cut the onions in half, peel and thinly slice. Peel the potatoes, cut in half lengthways, and then across in slices 5mm thick. Toss with ½ teaspoon salt and leave to stand in a colander.

Heat the olive oil in a large heavy saucepan and when hot but not smoking add the onions with a pinch of salt. Give them a good stir, reduce the heat to low, and cook very slowly for about 30-45 minutes until golden in colour and sweet in smell. Be sure to stir the onions every 5 minutes so they cook evenly and do not stick to the bottom of the pan. Remove from the heat, drain, and reserve the oil.

Meanwhile, cook the potatoes. A deep-fat fryer is perfect but for those without one, pour the sunflower oil into a similar-sized saucepan (never fill the pan more than half full) and set over a medium heat. The temperature is crucial as the potatoes should cook until tender without colouring, that is, simmer gently and not spit furiously. Drain in a colander. Strain the oil and keep it back for another occasion.

Break the eggs into a large mixing bowl and whisk briefly. Add the onions and potatoes and mix together. Taste for seasoning. The mixture may only need a little pepper.

Pour the reserved onion oil into a frying pan approximately 20cm across, and set over a high heat. When the oil begins to smoke pour the mixture in with one hand whilst shaking the pan with the other. Reduce the heat to low and cook for 3-5 minutes or until the underside is golden brown. Then take a plate of a similar size and rest it over the pan. With both hands and two kitchen cloths carefully invert the tortilla on to the plate. The uncooked side will still be fairly runny so watch out! Turning the tortilla helps to give it its distinctive shape.

Turn the heat to high again, pour a little extra olive oil into the frying pan and slide the tortilla back into the pan runny side down and tuck in the edges. Cook for another 3 minutes. Both sides of the tortilla should now be golden brown in colour. If not, it requires a little more cooking. The tortilla will be cooked if the middle feels solid. If it still feels a little soft, continue to cook until firmer. Remove from the pan and slide on to a plate. Allow to cool for a few minutes before cutting into diamond shapes.