Tortilla Espanola

2 tablespoons olive oil
6 medium potatoes, peeled and thinly sliced
1 large onion, finely chopped
1/2 teaspoon salt
1/2 teaspoon pepper
6 large eggs
1/2 teaspoon salt
2 tablespoons olive oil

Heat 2 tablespoons olive oil in cast iron skillet. Add next 4 ingredients. Cook, stirring constantly, over medium heat 4 to 5 minutes; cover and cook 5 minutes or until potatoes are soft, but not browned.

Combine eggs and 1/2 teaspoon salt in a large bowl; beat until frothy. stir in potato mixture. Heat clean cast iron skillet until hot enough to sizzle a drop of water. Add 2 tablespoons olive oil; rotate pan to coat bottom and sides. Pour egg mixture into skillet. Cook 5 minutes over medium-low heat. Bake at 375 degrees F for 10 minutes or until set. Loosen with a spatula; invert onto serving plate.