On a large tray spread the sea salt to give a thin layer the put the potatoes on the tray. Cover with foil and bake in the oven until soft. I prefer this method to boiling as it helps prevent the potatoes being too wet and difficult to work with later.
When the potatoes are cooked allow to cool slightly then scoop out of the skins and push through a sieve into a clean bowl. This is much easier to do when potato is still hot. Set aside and allow to cool.
Meanwhile put a large pot of water on to boil and heavily salt.
Weigh out 500g of the potato and discard the rest, You will likely be left with 550g after passing. Add the sifted flour and Cheddar and mix well. Add the egg yolks and mix to a soft but not sticky dough. Roll out into sausages about 2cm in diameter then cut into 2cm lengths and place on a tray lined with baking parchment while cutting the rest.
To cook, drop a little at a time into the simmering water. Remove the Dumplings as soon as they float, this usually takes about 1 minute. Place in a bowl of iced water . Repeat for the rest of the mix.
Dry off the dumplings and fry in a little rapeseed oil.