Mix yeast, 30 ml lukewarm water and sugar. Put the flour in a bowl. Gradually stir in the yeast mixture and milk. Cover and leave to rise in a warm place for about 30 minutes. Melt butter and let it cool down.
Add butter, egg yolk, some salt and 1 tablespoon of sour cream to the dough and mix well. Heat some fat in a pan. Add the dough by the spoonful and bake on both sides until golden brown. Arrange 2-3 blinis with salmon and remaining sour cream on small plates. Garnish with dill (possibly also dill flowers) and lemon wedges