a 1/4-ounce package (2 1/2 teaspoons) active dry yeast about 2 cups sour cream as an accompaniment about 4 ounces each black caviar, golden caviar, and salmon roe
In a large bowl proof the yeast with 1/2 tablespoon of the sugar in 1/3 cup lukewarm water for 10 minutes, or until it is foamy. Stir in 1 cup of the milk, heated to lukewarm, the remaining 2 tablespoons sugar, 2 tablespoons of the butter, and the buckwheat flour, beat the batter for 1 minute, and let it rise, covered with plastic wrap, in a warm place for 2 hours or chill it, covered tightly, overnight. (Chilling overnight produces a tangier flavor. Let the batter come to room temperature before continuing with the recipe.) Stir in the remaining 1 cup milk, heated to lukewarm, the all-purpose flour, the salt, and the yolks, beat the mixture for 1 minute, and let it rise, covered with the plastic wrap, in a warm place for 1 hour, or until it is double in bulk and bubbly. In a bowl beat the cream until it holds soft peaks and fold it into the batter. In a metal bowl beat the egg whites until they just hold stiff peaks and fold them into the batter gently but thoroughly.
Heat a griddle or large skillet over moderate heat until it is hot, brush it lightly with the additional melted butter, and spoon tablespoons of the batter onto the griddle, spreading them to form 3-inch rounds. Cook the blini for 1 minute on each side, or until the undersides are golden. Transfer the blini as they are cooked to a platter and keep them warm, covered with a kitchen towel. Make blini with the remaining batter in the same manner, brushing the griddle lightly with the butter as necessary. The blini may be made 2 days in advance and kept covered and chilled. Reheat the blini, covered with foil, in a 350 F. oven for 10 to 15 minutes, or until they are warm, or microwave them on a microwave-safe platter, covered with microwave-safe plastic wrap, at high power (100%) for 2 minutes, or until they are warm.
Arrange 3 or 4 blini on each of 18 small plates, top them with some of the sour cream, and arrange some of the caviar decoratively on the sour cream.
Serves 18 with blini to spare.