Warm the Milk to about 100–110°F (38–43°C), stir in a pinch of the Sugar and sprinkle the Active Dry Yeast over the surface; let sit 5–10 minutes until foamy.
In a large bowl whisk together the All-Purpose Flour and Salt; in a separate bowl beat the Eggs and then fold them into the foamy milk mixture.
Combine the wet and dry ingredients, whisking until you have a smooth, slightly thick but pourable batter; cover and let rest in a warm spot for 45–60 minutes until the batter is aerated and slightly risen.
Melt about half of the Unsalted Butter and stir it into the batter to enrich it, reserving the remainder for cooking and finishing.
Heat a nonstick skillet over medium heat and brush it lightly with Neutral Oil (or a little of the reserved butter).
Drop tablespoonfuls of batter into the skillet to form small pancakes (blini); cook until bubbles form on the surface and the edges look set, about 1–2 minutes.
Flip each blin and cook another 45–90 seconds until golden and cooked through; transfer to a warm plate and keep covered while you finish the rest.
Serve the blini warm with a dollop of Sour Cream and an extra pat of butter, or top with jam, caviar, smoked fish, or fresh herbs according to your preference.
