In a bowl, beat the eggs with freshly grated cheese. Season with salt.
Heat the olive oil in a nonstick frying pan. Add the potatoes, red peppers, and onions, and cook for 5 minutes, or until the vegetables are soft.
Pour the egg mixture into the pan. With a fork, evenly distribute egg mixture to the edges of the pan.
Cook for approximately 3 to 4 minutes with a lid on. Carefully flip the frittata over and cook for another 2 minutes. Serve hot or cold.