Cook the potatoes with the skin on in salted water for about 20 to 25 minutes.
While the potatoes are cooking seperate the whites from the yolks. Use a hand mixer or kitchen aid and whisk the whites in a kitchen bowl until soft peaks form. Set aside in the fridge.
When the potatoes are soft, strain off the water and let the potatoes cool for 5-10 minutes.
When the potatoes have cooled slightly, peel them and push through a potato ricer into a mixing bowl (alternatively use a masher or sieve). Aim for 390g/13.8oz of riced potatoes.
While they are still hot add the flour, baking soda, egg yolks and crème fraiche. Mix well and season with salt.
Carefully spoon by spoon add the beaten egg whites to the potatoes and mix until a smooth batter has formed.
Place the potato mixture in a piping bag. Pipe the batter onto a wide non stick pan or cast iron pan, the size of a bite-size blinis. Keep the heat on low at all time, that way they will brown evenly and cook inside.
Cook them approximately 4-5 minutes on each side until they have taken on a nice brown colour.
Use the blinis while still warm or place them on a wire rack to cool. If you cool them down they will slightly deflate so don't be surprised.