Peel potatoes and cut into quarters, lengthwise. Then cut into thin slices.
2 medium potatoes
Heat 2 tablespoons of oil in a skillet over medium heat. Add onions and cook until soft. Add the potato slices. Cook for some minutes until onions are caramelized and potatoes are browned.
4 tablespoons oil, 1 medium white onion
Remove the skillet from heat. In a large bowl, beat the eggs. Add the cooked potatoes and onions, and the bell peppers. Stir well until well distributed. Season with salt and pepper.
5 medium eggs, ½ cup green bell pepper, Salt and pepper
Return the skillet to the stove and turn the heat to medium-low. Add the remaining 2 tbsps. of oil to the skillet and tilt it around to make sure the bottom and sides are coated with oil.
4 tablespoons oil, 1 tablespoon parsley
Pour the mixture into the skillet, and spread evenly. Sprinkle with chopped parsley. Cover with the lid and turn the heat to low.
Cook until the egg has completely set (about 5-10 minutes), gently shaking the pan every now and then. When the frittata is easily pulled off from the bottom, it is ready to be turned.
Place a plate on top of the skillet and flip both over so the frittata is transferred on the plate. Gently slide it back to the skillet to cook it for another 2-5 minutes, uncovered,
Once cooked, you can flip it over directly to a serving plate or a cutting board.