Viennese herring salad
First, sift the flour into a bowl. Dissolve the sugar and yeast in lukewarm milk and stir into the flour. Sprinkle the batter with flour, cover with plastic wrap and leave to rise in a warm place (approx. 25 °C) until it has expanded to double its bulk.
For the main pastry, mix together the egg, egg whites and the milk. Put the dough in a bowl and sift flour over it. Add the egg-milk mixture, and knead. Add the butter gradually and finally, a pinch of salt. Knead the dough (either by hand or on the lowest setting of a blender) for 15–20 minutes until smooth and elastic. Sprinkle with flour, cover with plastic wrap and leave it to rise for 20–25 minutes.
Preheat the oven to 220 °C. Work the dough through thoroughly. Again, cover with plastic wrap and leave it to rise again for 20–25 minutes. Put the dough in a baking tin, sprinkle with some flour, and again cover and leave until it has risen to three-quarters its bulk.
From the mass, now make small mounds or small plaited loaves about 40 g in weight.Whisk the egg whites and milk, and brush over the mounds. Place a tray filled with water on the lowest shelf of the oven. Reduce the temperature to 180 °C. Put the brioches on a baking tray covered with baking paper and bake golden brown for about 12 minutes. Place the brioches on a cake rack and allow to cool.