Sift dry ingredients into a bowl. Beat eggs well and add to dry ingredients. Peel and grate onion. Add to mixture in bowl with parsley. Mix well. Wash, peel and grate potatoes. Put in cloth or absorbent paper and squeeze out excess liquid. Add potatoes to egg mixture and beat thoroughly with a wooden spoon. Heat butter in a frying pan. Spoon about 2 tablespoons batter into pan and flatten slightly with a spoon. Cook over medium heat until golden brown and crisp on one side. Turn carefully and brown on other side.