Special equipment: A small skillet (preferably a well-seasoned cast-iron skillet), a piping bag fitted with a medium tip (or a sandwich bag with a trimmed corner)
Over medium-high heat, bring the milk and butter to just below a boil. Cool until lukewarm.
Combine the buckwheat flour, sugar, and salt. Set aside.
In a separate small bowl, combine the yeast and lukewarm water. Allow the yeast to activate for 5 minutes in a warm place (see Cook's Note*).
In a large bowl, beat the egg yolk until light yellow. Drizzle the milk and butter mixture slowly into the yolk while whisking. Add the dry ingredients and stir to combine. Cover tightly with plastic wrap and put in a warm place until doubled in size.
Whisk the egg white until soft peaks form. Fold the egg white into the batter. Cover the batter again and allow it to regain its original volume, about 10 to 15 minutes.
Preheat a skillet and lightly brush it with the clarified butter. Spoon 1 tablespoon portions of the batter into the skillet (see Cook's Note**). Lightly brown on both sides.
Spoon 1 teaspoon of the smoked salmon cream cheese mixture over a blini. Garnish with fresh dill and serve.
In a medium bowl cream together the cream cheese, dill, lemon juice, and lemon zest. Gently fold in the smoked salmon.
*Once yeast is combined with liquid, it should be kept between 80 to 115 degrees F until cooking to prevent killing the yeast cells. **Since the dough can be gooey, it's easiest to scoop and drop spoonfuls of dough by twirling the spoon. ***Use the Herbed Cream Cheese just after the mixture has been assembled so that it's easier to pipe. **** Clarified butter is unsalted butter that has been slowly melted, separating the milk solids from the liquids. After removing any foam off the top, the golden butter is poured or skimmed off the milky residue. Clarified butter is used to cook at higher temperatures because it has a higher smoke point.