Spanish Tortilla with Tomato Salad

Heat 1 cup of olive oil in a large non-stick skillet over medium heat. Add the sliced potatoes and onions. Cook gently, stirring occasionally, until the potatoes are very soft but not browned (about 20-25 minutes). They should be easily pierced with a fork.

Remove the potatoes and onions from the oil with a slotted spoon and drain them in a colander over a bowl to remove excess oil. Reserve the oil for later use.

In a large bowl, whisk the eggs with salt and pepper. Add the drained potatoes and onions to the bowl with the eggs and mix well. Let the mixture sit for a few minutes to allow the potatoes and onions to absorb some of the egg.

Heat about 2 tablespoons of the reserved olive oil in the same skillet over medium heat. Pour the egg and potato mixture into the skillet. Cook for about 5-7 minutes, until the bottom is set and golden brown. Gently shake the pan occasionally to prevent sticking.

Place a large plate over the skillet and carefully invert the tortilla onto the plate. Add another tablespoon of the reserved oil to the skillet. Slide the tortilla back into the skillet, uncooked side down. Cook for another 5-7 minutes, until the other side is set and golden brown. For a firmer tortilla, you can optionally finish it in a preheated oven at 350°F (175°C) for 10-15 minutes.

While the tortilla is cooking, prepare the tomato salad: Slice the tomatoes into wedges or chunks. Combine them with the red onion, parsley, sherry vinegar, and olive oil in a bowl. Season with salt and pepper to taste.

Remove the tortilla from the skillet and let it cool slightly before slicing into wedges. Serve warm or at room temperature, accompanied by the tomato salad.