Mix the cornmeal and salt and stir in the boiling water. Cover and let stand for 10 minutes. Beat in the eggs one at a time; then slowly stir in the milk. Mix in the flour and 2 tablespoons melted butter; beat until the mixture is smooth. The batter should be the consistency of heavy cream; if it is too thick, thin with a little more milk.
Brush a well-seasoned crêpe pan with clarified butter and heat. When the pan is hot, pour in about 3 tablespoons batter and tilt the pan to distribute the batter evenly. Cook until the underside is lightly browned, 2 to 3 minutes. Turn and cook the other side another 1 to 2 minutes.
Put each blini on a hot plate and pour 3 tablespoons clarified butter over the blini. Put 1 tablespoon sour cream in the center of each blini, then 1 tablespoon salmon caviar in the center of the sour cream, then 1 teaspoon (or more) black caviar in the center of that. Put 3 slices sturgeon around each blini and serve immediately.