Tortilla Española - Spanish Omelet is one of Spain's most popular tapas. It's delicious, versatile, and made with only potatoes, onion, eggs, and extra-virgin olive oil.
Cut peeled potatoes in half lengthwise. Cut each half lengthwise again. Then slice crosswise thinly.
Place extra-virgin olive oil into 10-inch nonstick skillet. Heat over medium-low heat. Once heated, add potatoes to oil and stir gently to coat. Cook for 5 minutes.
Add 1/2 teaspoon salt and sliced onions to skillet and stir gently. Cook for about 15 minutes, stirring occasionally, until potatoes are tender and just beginning to turn golden.
Strain potato/onion mixture in a colander, reserving oil. I place my colander inside a bowl to collect the oil.
In another large bowl, whisk eggs with 1/2 teaspoon salt. Add potato/onion mixture to eggs and toss gently.
Place same nonstick skillet back on stove and heat over medium heat. Add about 2 Tablespoons reserved oil to skillet.
Once heated, add egg/potato mixture to skillet. Mix quickly as if scrambling them until eggs just begin to set. Then stop mixing and push down edges of omelet around the skillet to help form smooth, round omelet shape.
Once eggs look almost set but still wet, place a large dinner plate or other plate (slightly larger than skillet) upside-down over skillet. With one hand gripping skillet handle and the other supporting back of plate, quickly flip omelet over onto plate. Lift skillet off and place back on stove. Slide uncooked side of omelet into bottom of skillet to finish cooking, another 3 minutes or so.
Serve warm or at room temperature.