First peel the potatoes and cut them into not too small cubes. Then cook as boiled potatoes with 2 teaspoons of salt (takes about 20 minutes).
Let cool in a bowl. Now add the remaining salt, pepper, lemon juice, corn, kidney beans, onion cubes and the oil. Spread 1 packet of salad spices over the top. Pluck the plucked parsley and add to it. Mix everything carefully and season with sumac at the end.
Tip: Depending on your needs, you can also mix in finely chopped gherkins.