Preheat your waffle iron to the desired setting for a crisp waffle.
Grate the potatoes and onion using a box grater, combining different textures by using both medium and small holes.
In a large bowl, mix together the grated potatoes, onion, salt, pepper, egg, and flour. Drain any excess liquid from the mixture.
Brush the preheated waffle iron with oil to prevent sticking. Place a portion of the potato mixture into the iron, spreading evenly. Close the lid and cook until the waffles are golden and crisp, about 5-8 minutes.