Dissolve the yeast in 2 fl oz (60) ml warm water. Then add the remaining water, mix with sugar and 4/5 cup (200 g) flour. Mix well and add salt and fat. Separately beat the egg whites with a pinch of salt to snow add it to the dough gently.
Add the remaining flour and knead an elastic dough. Shape it into a ball, transfer it to an oiled bowl and brush the top with oil. Cover with a towel and let rise in a warm place until doubled in volume. From the risen dough, shape 16 to 20 smooth balls. Arrange them in a pan with baking paper, some distance off each other.
Cover and leave it to rest. Brush them with beaten yolk and put them to bake in a preheated 428°F (220 °C) oven. Put a fireproof container with water in the oven. Vienna bread takes about 20-25 minutes for baking - until it swells very well and acquires a golden color.