In a large bowl, beat the butter, egg yolks, sugar and salt together, then add the sour cream and the yeast mixture and blend in the flour until you have a dough.
(egg yolks, sugar and salt together; add; the sour cream and the yeast mixture and blend; L:in the flour; T:then) (you; have; a dough)
egg yolks, sugar and salt together you
add have
the sour cream and the yeast mixture and blend L:in the flour T:then
a dough