In a large bowl beat together the egg yolks, sour cream, white sugar, vanilla and whiskey until smooth. Stir in flour until dough is stiff enough to knead. Turn out onto a floured surface and knead until smooth. Knead in additional flour if necessary. Divide dough into 3 or 4 pieces and roll each ball on floured surface. Cut into strips about 8cm long then make a slit long ways down the middle. Pull one of the ends through like a bow.
Place into hot oil and deep fry until golden brown. Let drain on paper towels and sprinkle with icing sugar.