Cream the yeast with a little milk, then add the remaining milk, the egg yolks and sour cream.
Sift the flour and salt into a bowl and add the yeast mixture. Stir to make a thick batter. Leave for at least 1 hour in a warm place. The batter should now look bubbly. Stir well. Just before cooking, whisk the egg whites until stiff and fold them into the batter.
Heat a little oil in the pan and pour off any excess. Then pour in a tablespoon of batter. Turn the pancake over when it shows bubbles on the top side. Cook lots. One bliny is never enough.
Recipe courtesy of Jennifer Paterson and Clarissa Dickson Wright