Spanish Potato & Onion Omelet

In a large bowl, beat eggs with a pinch of salt until frothy. Set aside. In a 10-inch nonstick or well-seasoned carbon steel skillet, heat oil over medium-high heat. Add potatoes and onions and stir occasionally, until potatoes and onions are tender, about 25 minutes. Set a fine-mesh strainer over a heatproof bowl and drain potatoes and onions of excess oil. Reserve oil. Transfer potatoes and onions to a medium bowl and season with salt, stirring well to combine. Beat eggs vigorously to re-froth, add potato and onion into the bowl with the beaten eggs and combine. Set aside for 5 minutes.

Wipe out the skillet. Add 3 tablespoons of reserved frying oil to the skillet and set over medium-high heat until shimmering. Pour egg mixture into skillet and cook, shaking pan rapidly, until bottom and sides begin to set, about 3 minutes. Using a spatula, press the edges in to begin to form the omelet’s puck shape. Continue to cook, adjusting heat lower to prevent the bottom of the omelet from burning, until beginning to set around edges, about 3 minutes longer.

Carefully and in one very quick motion, invert the omelet onto a flat, overturned plate from the skillet. Add 1 more tablespoon reserved oil to the skillet and return to heat. Carefully slide the omelet back into the skillet and continue to cook until the second side is beginning to firm up, about 2 minutes. Again press the sides down lightly and continue to cook until lightly browned on the second side, but still tender in the center when pressed with a finger, about 2 minutes. Flip the omelet two to three more times during these last minutes of cooking to help cook the center more evenly and reinforce the shape. Carefully slide the omelet out of the skillet onto a clean plate. Let it stand at least 5 minutes before serving.