Tortilla de Patatas

In a large skillet or pan, heat olive oil over medium and gently fry thinly sliced potatoes until tender and just starting to break apart. Transfer potatoes to a bowl lined with paper towels to absorb excess oil. In a separate pan, caramelize thinly sliced onions until deeply golden and sweet. (You can do this first tbh) Remove the paper towels and combine the potatoes with the caramelized onions, 4 eggs, 3 yolks, and a generous pinch of salt. Stir gently and let the mixture rest for 5 minutes so the potatoes absorb the egg. Preheat an 8-inch nonstick skillet over medium heat with a little of the reserved oil. Pour in the mixture, smooth the top, and use a spatula to round the edges. Cook for 1 minute per side for a soft, custardy center, then flip carefully using a plate, lid, or cutting board. Cook longer if you like your tortilla more set. Once golden on both sides, plate and let rest before slicing in. Tortilla should be served at room temperature.