Onions are cleaned and cut into thin rings. Place in a small bowl and pour the soka of lemons. Watermelon is cleaned of seeds and cut into cubes. The feta cheese is cut into small pieces or cubes. In the bowl put the watermelon, the feta cheese and onions. Pour with soka of lemons. Parsley and mint finely and add to the salad. Salad sprinkled with olive oil and sprinkle with olives. Season with ground black pepper.