It's Karen Martini's five-ingredient potato party, and everyone's invited.

“This tasty recipe comes courtesy of my friend Emma Warren, who is my go-to for the traditional dishes of Spain,” says Karen Martini. “For best results, eat on the day and don’t refrigerate.”

Ingredients
Serves 8–10

  • 250 ml (8½ fl oz/1 cup) extra-virgin olive oil
  • 1.2 kg (2 lb 10 oz) boiling (waxy) potatoes (such as desiree or Dutch cream), peeled, cut in half and sliced 2 mm (⅛ in) thick
  • 1 large onion, finely sliced
  • 12 eggs
  • ½ teaspoon flaked salt, plus extra, to season

Method

  1. Heat the oil in a 24 cm (9½ in) non-stick or well-seasoned heavy-based frying pan over a medium heat. Add the potato and mix through to coat. Add the onion, stir through to coat, then reduce the heat to low.
  2. Cook until the potatoes are soft but not browning or breaking apart, and the onion is translucent, 10–15 minutes. Carefully turn the mixture at regular intervals with a flat spatula for even cooking. Tip into a colander set over a bowl, reserving the oil.
  3. In a large bowl, beat the eggs with flaked salt, then add the potato mixture. Stand for 10–15 minutes to allow the potato to absorb some of the egg.
  4. Add 3 tablespoons of the reserved oil back to the frying pan over a low heat. Add the egg mixture and cook until the edges start to firm up, about 2 minutes.
  5. Reduce the heat to low, then stir for 1 minute to move the heat through the mixture and break up the cooked egg from the base, stirring through the uncooked part of the mix. Flatten out the mixture once more. As it cooks, loosen the edges with a spatula, to allow some airflow and stop it sticking at the edges. Cook for 12 minutes, until the edges are well-sealed and golden. The top will still be a bit runny.
  6. Invert a dinner plate over the top, then place your hand on top and flip the whole thing over so the tortilla is on the plate. Take the pan off. Return the pan to the heat and add more of the reserved oil. Slide the tortilla back into the pan, tucking in the edges with a spatula to cook the other side. Cook for a further 6–8 minutes, then shake the pan to make sure it is not stuck.
  7. Flip again onto a plate, then set aside for 15 minutes to finish cooking in the residual heat. It should be slightly runny on the inside. Serve sliced, with a sprinkling of salt flakes.

Another option

If you prefer your eggs really well done, or aren’t up for the flipping component, once the mixture is flattened out in the pan, bake it in a preheated 165°C (329°F) oven for 30–40 minutes.

Cook Green

This is an edited extract from Cook: Green by Karen Martini published by Hardie Grant Books. Photography: © Armelle Habib. The book is available in stores now including at great independent retailers such as Readings and Hill of Content.