A classic Spanish dish, this slow-cooked potato tart is made with thinly sliced potatoes, onion and egg. Simple to make, and utterly delicious hot or cold.
A Spanish tortilla consists of layers of soft, creamy potato slices suspended in a set egg mix that has been browned in a frying pan. In order to achieve this creamy-crispy texture, the potatoes must first be cooked slowly in olive oil on a low heat. The gentle heating action effectively braises the potato, cooking it without browning – just like a duck confit, where duck fat is used as a cooking medium to the same effect. Once the potato is tender, it is drained and mixed with eggs before being fried and browned like a traditional omelette. Although a classic tortilla consists of just potato, egg and onion, it’s not uncommon to find variations that include roasted pepper slices or chopped, blanched spinach. If you want to include any extra ingredients, just make sure they are finely chopped so that the tortilla still holds together, and add them at them at the infusion stage.
Due to the long cooking time, it is important to use the right variety of potato. Potatoes are classified according to whether they are waxy (Charlotte, Jersey Royal, new potatoes), or floury (Desiree, Estima, King Edward, Maris Piper). Waxy varieties are higher in starch and lower in moisture. This gives them a firmer texture, and makes them suited to dishes where the potato needs to hold together or crisp up. Waxy potatoes are good for fries, potato salads, and Spanish tortillas. Floury varieties are lower in starch and higher in moisture. This means that they break down when cooked, resulting in a light and creamy texture with rough, broken edges. Waxy potatoes are good for mashed potato, baked potatoes, and roast potatoes.
Tips & Tricks
- Slice the potatoes thinly – this creates more crevices for the egg to ooze into and glue the tortilla together
- Drain the potatoes well – too much oil will stop the egg from setting
- When frying the tortilla, heat the pan to sizzling point – this creates an instant seal when the mixture is added, preventing the egg from sticking to the bottom
- 300ml olive oil
- 1 onion (130g), peeled and finely chopped
- 750g waxy potatoes (Charlotte, Jersey Royal or new potatoes), scrubbed clean
- 6 medium eggs (55g each)
- 1 teaspoon salt
- 1/4 teaspoon freshly ground black pepper
- Saute the onion. Heat the olive oil in a heavy-based casserole over a medium heat. Add the onion and fry for about 5 minutes, until translucent but not brown.
- Cook the potato. Meanwhile, slice the potatoes on a mandolin grater (if you do not have a mandolin, use a food processor or slice as thinly as you can using a large knife).
- Add the potato slices, and flip with a fish slice to redistribute the onion through the potato. Adjust the heat to a gentle sizzle (about medium-low). Cook for 25 minutes, or until the potato slices are tender, but still retain their shape. Do not stir, as this may cause the potato to break apart. Instead, flip gently with the fish slice a couple of times during cooking.
- Once cooked, drain the potatoes and onions in batches in a colander set over a wide-mouthed jug, removing as much oil as possible. Reserve the drained oil for another project.
- Combine the ingredients. Crack the eggs into a large mixing bowl, and add the salt and pepper. Briefly whisk until blended to a uniform primrose colour. Add the potatoes and onions, and gently toss until evenly coated in egg. Leave the flavours to infuse for 10 minutes.
- Fry the tortilla. Heat a 20cm/8″ skillet over a medium-high heat. Add enough of the reserved oil to cover the bottom in a thin film – about 1 tablespoon. When a few drops of water sizzle and evaporate upon contact with the pan, pour in the omelette mix. Immediately turn down the heat to medium. Flatten the top by pressing down with the fish slice. Cook until the sides set – about 6-7 minutes.
- Run a palette knife around the sides, then invert onto a dinner plate. To do this, place the plate on top of the pan, then quickly flip the whole lot upside down. Remove the pan to reveal the perfectly cooked golden-brown bottom. Add a little more of oil to the pan. Once the oil is sizzling hot, gently slide the tortilla back into the pan to cook the other side for another 6-7 minutes. Push in the sides with the palette knife to get a nice rounded edge.
- Invert onto a dinner plate, and slice like a cake to serve. Can be eaten immediately, or left to cool and eaten at room temperature. The tortilla will keep well for up to 3 days in the refrigerator. For best results, remove from the refrigerator half an hour before serving.