To make the batter: Take a small bowl and sift sugar and all-purpose flour in it. Pour the yeast, and afterward warm milk ½ half cup; whisk the mixture until it becomes smooth.
Take a medium-sized bowl and blend the salt and buckwheat flour. Add the remaining milk and egg yolk; whisk both together until you get a smooth mixture.
Cover up two bowls using the plastic wrap and keep them aside at room temperature for at least one hour to four hours. Stream the yeast mixture in the buckwheat mixture after some rest duration, and whisk it well to combine thoroughly.
Take a small bowl and whisk the egg whites till some soft peaks form; scrape it off on the top layer of batter. Mix the heavy cream in the now-empty egg white bowl and whip it till some soft peaks form; scrape it upon the egg white, very carefully fold all the batters together.
Use plastic wrap and cover up both the bowls together and keep it aside for 1 hour at room temperature. Allow it to rest longer in a subtly cool place, which will help develop more flavor, for at least two to six hours, and the blini would also become crispier. You can store the batter for 24 hours; there will some slightly sourdough flavor. You can refrigerate the batter overnight if your kitchen place is warmer, and you can then bring it down to room temperature.
To cook: Take a small non-stick skillet and stream clarified butter or butter mixture in it, make sure it forms a very thin film. Stream about ½ tablespoon of batter in the hot fat and roll on about 1 ½-2 inches in diameter, if you want.
Keep cooking it until it takes golden brown color, flip over and again cook the other side to the point it turns golden brown, it should look entirely cooked at the center. Take out on a paper towel to gently drain, serve it while warm, along with a Crème Fraîche, two chive pieces and smoked salmon! Dab with caviar, if you would like to have something extra special.
Wine pairing for the dish: Champagne or Sparkling wine!