Boil the potatoes and peel them. Steam-cook the cauliflower after tearing it into rosettes.
Mash the vegetables and cool them. Break an egg on top, add the crumbled feta, season with salt and white pepper. Stir everything until homogeneous.
Mix together equal parts flour and breadcrumbs.
Heat the oil in a suitable frying pan.
Form meatballs from the mixture, dip them on both sides in the flour and breadcrumbs and fry until golden.
Drain the cooked meatballs onto paper towels.