Boil potatoes until nearly done (when pierced with a fork the center will still feel slightly undercooked). Cool potatoes. Peel and grate on the largest holes of a grater.
Saute onions in butter on low heat until golden. Stir flour slowly into cooked onions. Add pepper and salt. Cook for 1 minute.
In a large bowl, mix potatoes, onions and eggs. Form into 12 patties.
In a large skillet, on medium-low heat, cook patties in butter on both sides until deep golden brown (do not crowd, you may need to cook in batches).