Warm the Whole Milk to lukewarm (about 100–110°F / 38–43°C). Sprinkle the Active Dry Yeast and a teaspoon of the Sugar over the milk, stir gently and let sit 5–10 minutes until foamy.
In a large mixing bowl combine the Buckwheat Flour, All-Purpose Flour and a pinch of Salt.
Beat the Eggs lightly and whisk them into the milk–yeast mixture, then pour the wet ingredients into the dry flours and stir until a smooth batter forms. Stir in 2–3 tablespoons of melted Unsalted Butter and adjust consistency with a splash more milk if too thick.
Cover the batter and let it rest in a warm place for about 45–60 minutes, until slightly risen and bubbly — this will yield tender, airy blini.
While the batter rests, hard-boil 2–3 extra eggs if you like a traditional garnish; cool, peel and chop or slice when ready. Finely dice the Red Onion, chop the Dill and Chives, and zest and squeeze a little of the Lemon to finish.
Heat a nonstick skillet or crepe pan over medium heat and add a small knob of Unsalted Butter to coat. Spoon tablespoon-sized portions of batter into the pan to form small blini (about 2–3 inches across). Cook until bubbles form and edges set, 1–2 minutes, then flip and cook the other side until lightly golden. Keep cooked blini warm in a low oven while you finish the batch.
To assemble, place a warm blini on a platter, add a small dollop of Crème Fraîche, top with a teaspoon or two of Black Caviar, then garnish with a few chopped pieces of hard-boiled egg, a scattering of Red Onion, a pinch of Dill and Chives, and a tiny squeeze or zest of Lemon.
Serve immediately so the blini are warm and the caviar is chilled — offer extra Crème Fraîche, chopped herbs and lemon wedges at the table for guests to customize.
