Whisk the eggs with the milk and sour cream. Whisk until smooth. In a separate bowl mix the 2 flours and salt. Make a well in the centre and add the liquid. Using a dough scraper mix the dough until fully incorporated. Whisk in the baking powder a few minutes before you are ready to cook your blinis.
In a non stick pan add a few knobs of butter and when foaming add the mixture with a tablespoon leaving a gap between each one. When they start to bubble in the middle they are ready to flip. As soon as you turn them in the pan they will rise instantly and double in size. Remove from the heat and dab away any excess butter with a piece of kitchen paper.
Chop the chives and mix through the creme fraiche. Served the blinis with a dollop of creme fraiche and smoked salmon.
«Make the batter well in advance, then just add the baking powder at the last minute.»