In a large bowl, mix together the flour, cornmeal, salt and baking powder. Add potatoes, 1/3 cup of oil, eggs and onion and mix until evenly blended.
Heat 1/4 cup of oil in a large skillet over medium-high heat. Drop heaping tablespoons of the potatoes into the hot oil, flattening slightly. Cook until browned on the bottom and then flip and cook on the other side. Keep in a warm oven while frying the rest.