Pare and grate potatoes into a mixing bowl. Squeeze out liquid. Peel and grate onion into potatoes. Add eggs, flour, and salt and stir to make a smooth batter that will drop heavily from the spoon. Heap the shortening in a heavy frying pan using enough to cover the pancakes amply. Drop the batter from a spoon into the hot shortening, making pancakes 8 cm in diameter. Fry over moderate heat until brown on the underside, turn to brown. Life out and drain off excess fat on paper towel. Pancakes fried in deep fat should be puffed and crisp. These pancakes may also be baked in a shallow baking pan for 45 minutes at 180ºC until nicely browned. Cut into squares and serve hot. They may also be put into a well greased small muffin pan and baked 45 minutes at 180ºC .