Soften yeast in warm water, sift flour and salt in mixing bowl. Cut in butter and shortening until size of peas. Blend eggs, sour cream, 1 tsp vanilla, yeast and water together. Add to dry mixture gently so that you keep the butter in little chunks.
Chill, wrapped in plastic wrap for two hours or up to 4 days.
Divide into two balls. For each ball, roll out into a 6 x 12 inch rectangle. Sprinkle with some of the vanilla sugar, fold in thirds, turn. Do this three or four times. Roll out one more time and cut into 12 equal strips 1 X 6 inches. Twist, roll in vanilla sugar and put on cookie sheet. Do the second ball or save it for another day. The recipe makes about 24 twists.
I tried the recipe using "lite" sour cream and it was too sticky. The dough should not need any flour because you are using the sugar to keep the dough from sticking to the board.
Bake at 375 for 15 to 20 min. These should be lightly browned, do not overcook. You will notice that there are little layers of dough with sugar in between.
Enjoy! Emily Jorge