Swirl 2 tablespoons of extra virgin olive oil in a 10-inch, heavy-bottomed, non-stick skillet over medium high heat. Add in the potatoes and onions and 1 teaspoon of the kosher salt. Toss to evenly distribute the salt and oil. Cook, turning frequently with a flexible spatula, for 5 to 6 minutes, then toss in the garlic and stir until fragrant. Put a lid on the pan, turn the heat to medium low and cook for another 15 to 20 minutes, opening and flipping the contents around, or until the potatoes are tender. Let them cool without the lid for 5 minutes.

While the potatoes cool slightly, whisk the remaining salt,eggs, chopped parsley, and black pepper in a large mixing bowl until even in colour. Toss in the potatoes and onions and gently mix to combine thoroughly. Add the remaining olive oil to the pan and return it to medium heat. Pour the egg and potato mixture into the pan and let it cook, undisturbed, until the eggs on the bottom begin to set, or about 2 minutes. Slide a flexible spatula under part of the cooked egg. Lift the cooked bit gently and tilt the pan to allow the uncooked, liquid egg from the top to pour under it. Repeat this procedure around the edge of the pan until all the pools of uncooked egg have been cooked this way and the tortilla is completely set on the sides. Slide the Spanish Tortilla onto a heat proof plate. Flip the pan over the tortilla and, holding the plate tightly to the pan, invert it so the uncooked portion of the tortilla is now face down in the pan. Return the pan to medium low heat for 2 minutes, or until the bottom side of the tortilla is set up.

Allow the Spanish Tortilla to cool for at least 20 minutes before turning out of the pan and slicing.

If you prefer, you can serve topped with diced bell pepper, arugula or mixed greens, and thinly sliced prosciutto or Iberico ham.