Ingredients

   
8 large eggs
  Kosher salt
475g extra-virgin olive oil
700g Yukon Gold potatoes, peeled, halved, and thinly sliced crosswise
350g yellow onions, thinly sliced
  Aioli, for serving

Steps

  1. Beat eggs vigorously with a large pinch of salt until frothy. Set aside.

  2. Heat olive oil in a 10-inch nonstick or well-seasoned carbon steel skillet over medium-high until shimmering. Add potatoes and onions. Regulate heat so they bubble gently but not vigorously. Cook, stirring occasionally, until meltingly tender and potatoes are breaking apart, about 25 minutes.

  3. Drain potatoes and onions through a fine-mesh strainer over a heatproof bowl. Reserve the oil. Season potatoes and onions generously with salt.

  4. Re-froth the eggs, then fold in the potato-onion mixture. Stir until thoroughly combined. Rest 5 minutes.

  5. Wipe out skillet. Add 45g reserved oil and heat over medium-high until shimmering. Scrape in the egg mixture. Cook, shaking and swirling the pan, until bottom and sides begin to set, about 3 minutes. Use a spatula to press edges inward to form a puck shape. Continue cooking about 3 minutes more.

  6. Place a large flat plate over the skillet and, in one quick motion, invert the tortilla onto it. Add 15g more reserved oil to the skillet. Slide tortilla back in. Cook until second side is lightly browned but center is still tender, about 4 minutes, pressing edges to reinforce the shape. Flip 2–3 more times if comfortable for a more evenly custardy center.

  7. Slide or invert onto a serving plate. Rest at least 5 minutes. Serve with aioli. Equally good at room temperature.

Notes

  • Pre-salting the eggs helps them retain moisture during cooking.
  • The large amount of olive oil is necessary for properly cooking the potatoes. Use a less expensive EVOO — heat kills the nuances of pricier oils.
  • Save the leftover frying oil — it’s infused with potato and onion flavor and is excellent for dressings, pesto, or more tortillas.
  • Flip technique: plate on top, hand on plate, one fast motion. Do it over the sink. Use a towel.
  • Custardy center (jugosa) or fully set (cuajada) — your call. Less cooking = runnier.
  • Leftovers keep refrigerated up to 3 days. Serve at room temperature.