In a large bowl mix together the sugar and dry active yeast. Pour over 50g / 1.8 oz lukewarm water and combine well. Put aside for 10 minutes.TipThe water should not be too hot, because it will kill the yeast. Make sure it has around 35°C / 95 °F.
In a small saucepan, over a medium high heat warm the milk, so that it becomes lukewarm. Pour the milk over the yeast mixture, combine well, using a wooden spoon. Add the flour, combine well, using a wooden spoon. Put in small cubes of softened butter and lightly rub into the flour mixture using your fingertips until there are no more big lumps of butter. Start kneading with your hands. Knead on a clean work surface for about 10 minutes.TipThe milk should not be too hot, because it will kill the yeast. Make sure it has around 35°C / 95 °F.
Shape the dough into a smooth, round disc. Put it back to your large bowl, cover with a plastic wrap or a linen/cotton cloth. Leave it proof for about 60 minutes at room temperature, or until double the size.
Transfer the dough to the floured work surface. Divide the dough into 7 equal parts, using a metal dough scraper or a sharp knife. Each bun should weight around 120 g / 4.2 oz. Take each portion of dough and roll between your hands until you get a perfectly round ball. Put on the prepared baking tray, lined with parchment paper.
Cover with a kitchen cloth or plastic wrap and let rise at a room temperature for about 35 minutes, or until double the size. Preheat the oven to 200°C / 395 °F.TipAllow a little space between the buns, so that they have enough room to rise.
Brush the egg wash lightly over the buns twice. Sprinkle some sesame seeds or nigella seeds all over the buns. Place the buns in the preheated oven, pour a cupful of water onto the hot roasting pan at the bottom of the oven and place the buns one grid higher. Bake the buns for about 15 minutes on 190°C / 375 °F, remove the roasting pan and continue to bake for another 10 minutes or until golden brown. Leave the buns rest for half an hour on a wire rack.
Eat the buns right away or store them in airtight container and freeze for up to 3 months.