The original blini (the word literally means ''yeast pancakes'') were made with buckwheat flour. Today, as in this recipe, white flour is often added to yield lighter blini.
1 1⁄4 tsp. active dry yeast
1 cup lukewarm milk
1⁄2 cup buckwheat flour
1⁄2 tsp. sugar
1⁄4 tsp. salt
2⁄3 cup all-purpose flour
2 tbsp. sour cream
1⁄4 cup heavy cream
2 eggs, lightly beaten
1 tbsp. unsalted butter, melted
1. Combine yeast and milk in a large bowl. Mix well, then add buckwheat flour, sugar, and salt. Mix thoroughly, cover with plastic wrap or a clean dish towel, and set aside to rise until bubbles appear on surface, about 1 hour.
2. Add all-purpose flour, sour cream, heavy cream, eggs, and butter. Mix well, cover, and set aside to rise for 2 hours more.
3. Heat 1 tbsp. oil in a large nonstick skillet over medium heat. Cook blini a few at a time (adding oil as necessary). Spoon batter, 1 tbsp. at a time, into hot pan and smooth with back of spoon (blini will flatten as they cook). Cook until edges brown and bubbles appear on surface, about 1 minute. Flip blini; cook for 30 seconds more. Transfer finished blini to a plate and cover with a clean dish towel while finishing cooking. Serve blini warm, brushed with melted butter if desired, and topped with caviar.