Tortilla Espanola (spanish-style Potato Omelet)

In a large nonstick pan, heat 2 tablespoons of the olive oil. Add the onions and bell peppers and cook over medium heat until translucent, 3-5 minutes. Stir in the potatoes and mix well. Add salt and cover. Cook over low heat until the potatoes are tender, 12-15 minutes. Stir the ingredients every 3-4 minutes to prevent sticking. Once the potato mixture is cooked, remove it from the heat and cool for 5 minutes. In a large bowl, whisk the eggs with the cilantro. Add the vegetable mixture and stir until combined. Add the remaining oil to the pan and heat until smoking. Add the egg mixture to the pan, lower the heat, and cook without stirring until the eggs begin to set. When the omelet starts to turn golden brown on the bottom, turn the omelet over. Cook until the second side develops the same color. If necessary, divide the oil and egg mixture between two pans. Serve very hot, warm, or at room temperature.