Dissolve yeast and sugar in 4 tablespoons of lukewarm water, leave to rise for 10 minutes. Warm the milk lukewarm. Put the flour in a bowl. Add 75 ml milk and yeast. Mix to a smooth dough. Cover and leave to rise for about 1 hour.
Stir the dough thoroughly. Separate the egg. Gradually stir in the beaten egg yolk, remaining milk, salt, 1 tablespoon sour cream and 1/2 tablespoon butter. Beat egg white until stiff and fold in carefully. Let the dough rise for another 30 minutes. Spread a large pan thinly with oil in portions and heat it up. Place 1 small ladle of dough per Blini in the pan and smooth it down. Fry over medium heat on each side for about 2 minutes. Remove the blinis and keep them warm. Before serving, brush the blinis with the remaining butter. Stir the remaining sour cream until smooth. Spread 1 heaped teaspoon of sour cream on each blinis.
Fry over medium heat on each side for about 2 minutes. Remove the blinis and keep them warm. Before serving, brush the blinis with the remaining butter. Stir the remaining sour cream until smooth. Spread 1 heaped teaspoon of sour cream on each blinis. Spread salmon, trout and herring evenly over the 12 blinis. Put 1/2 teaspoon of caviar on each piece of trout. Garnish the blinis with lemon wedges and dill
1 3/4 hours waiting time