TORTILLA DE PATATAS

500g agria potatoes 1 small onion

½ cup olive oil ½ tsp salt

4 large eggs

Peel the potatoes and onion and slice thinly with a sharp knife or mandolin.

Add the oil, potatoes and onion to a 20cm frying pan. Add a pinch of the salt, then place the pan over high heat. When the oil starts bubbling around the edges, lower the heat, cover with a lid or foil and cook for about 20 minutes, stirring occasionally, so the potatoes cook evenly.

They should be soft, but holding their shape and not browned.

Drain and reserve the oil, then tip the potatoes and onions into a colander.

Beat the eggs in a bowl with the remaining salt. Add the slightly cooled potato and onion to the egg.

Return the pan to the heat with 1½ tablespoons of the reserved oil. When very hot, tip in the egg and potato mixture. Cook for 2 minutes over high heat.

Turn the omelette over by placing a plate firmly over the pan. Flip the pan upside down so the omelette drops onto the plate. Return the pan to the heat, add another tablespoon of the reserved oil, then slide the omelette back into the pan. Cook for 2 minutes, shaking the pan so the omelette does not stick.

Lower the heat and cook for 1-2 minutes more, if you like – the Spanish prefer their omelettes runny in the centre.

To serve, cut into 4 wedges.

Drinks match: a small glass of lager.