Tortilla with prawns

Cut the onions into thin rings. Heat the oil in a pan and fry the potato and onion for about 20 minutes. Stir several times and reduce the heat to steaming after 3 minutes. Scramble the eggs in a large bowl and season with salt and pepper. When the potatoes are cooked, drain them through a sieve and collect the oil. Slowly stir the potatoes into the egg mixture. Then add the potato and egg mixture to the pan and fry for approx. 5 minutes over a low heat until the eggs have set. Fry the other side too until the tortilla turns golden brown. Serve on a plate with the prawns and garnish with tomato and parsley, if you like.