Start by combining all the dry ingredients in the bowl of your stand mixer. Mix all-purpose flour, milk powder, salt, and sugar.
Now add the starter, melted butter, and milk.
Knead the dough at low speed for 9-10 minutes until a smooth dough is formed. Quickly touch the dough, and it should not stick to your fingers. This way you know that the dough is ready.
Remove the dough into a greased bowl and cover with a cling wrap. Let the dough bulk rise at 85-95 0F for 2 hours and then put it in the fridge for the cold rise. Let it retard in the fridge overnight.
Next morning remove the dough onto a work surface and divide into 8 equal parts.
Shape each part into a long roll. Use a dough scraper to divide the dough into two equal hot dogs ( use either of the two methods shown in the post).
Place them on a baking tray lined with parchment paper.
Cover with the kitchen towel and let it proof in a warm place for 2-3 hours or until they double in size and become fuller.
Now preheat the oven to 375 0 F.
Bake them until golden brown. It would take about 40 minutes. Flip the tray in between.
Brush these gorgeous sourdough hot dog buns with melted butter as they come out of the oven.
Transfer to a cooling rack and let them cool for 10 minutes before filling.
Enjoy your homemade sourdough hot dog buns.