Spanish Omelette

Method

1. Peel 250 g of waxy potatoes and cut them into even rounds about 3 mm thick, then halve any wide slices. Peel and thinly slice 60 g of onion. Pat the potato dry in a tea towel.
2. Pour the 150 ml olive oil into a 20 cm non-stick or well-seasoned frying pan and warm it over medium-low heat. Slide in the potatoes and onion with 0.25 tsp of the salt — the oil should barely bubble, not sizzle hard.
3. Cook gently for 15-18 minutes, turning carefully every few minutes with a slotted spoon, until the potato is completely tender and crushes under a spoon and the onion is soft and sweet. Do not let anything colour beyond pale gold.
4. Tip the contents of the pan into a sieve set over a heatproof bowl and let the oil drain off for 2-3 minutes. Reserve the oil; wipe the pan clean.