Boil the potatoes in their skins in lightly salted water until soft.
Drain, peel the potatoes while warm, place in a bowl and mash.
Add the feta cheese crumbled, the spring onions or the onion, dill, lemon juice and egg.
Season with salt and pepper (not too much salt: the feta cheese is fairly salted already).
Cover the mixture and chill about 30 minutes.
Divide the mixture in walnut-size balls, and flatten them slightly so they look like little thick cookies (it helps to have a bowl with water on the table to clean the hands after making several patties: they get very sticky!).
Dredge with the flour.
Heat some oil in a frying pan (like 3 tablespoons) and fry the patties until golden brown on each side.