In a bowl mix together wheat flour, salt, yeast, sugar, milk powder, soaker and the room temperature tangzong.
Mix curd and baking soda until curd turns frothy.
Add it to the dough ingredients along with 2-3 tbs of water to make a slightly sticky dough.
Now transfer the dough to counter and knead for 10 minutes or until the dough passes the window pane test.
Place it in a well oiled bowl and rotate dough to coat it with oil.
Cover with cling wrap. You can set this on your counter until it doubles or place it in fridge for 6-8 hours for slow proofing. If placed in fridge, then you need to bring it to room temperature before shaping.
Once the dough is double and at room temperature, flatten it and divide it into 12 equal portions.
Roll each portion into a small tight ball with seam side down.
Arrange them in a greased 8" square tin or a loaf tin.
Again you can just proof it on counter until double or can refrigerate it overnight.
Preheat oven to 200°C.
If in fridge, allow it to come back to room temperature.
Brush the rolls gently with milk.
Bake the buns for 25-30 minutes or until the top is golden.
Remove form oven and immediately apply butter on top.
Remove from the pan to wire rack.
When warm, serve it with gravy or make vada pav or pav bhaji and enjoy...