Add the yeast, warm water and sugar to a bowl and allow this to froth for 30 mins
Add the baking powder, butter, salt and alternate with the milk and flour
Knead and if the dough is too dry, add a bit more milk
Transfer to an oiled bowl, cover with cling film and a towel and allow to rise for 2 hours in a warm place
Knead the dough and divide into 11 - 12 pieces
Cover and allow to proof again for 30 mins
To make the filling, heat some oil and add the diced onion and green chilli
Add curry leaves, ginger and garlic paste and the cooked potatoes
Add salt to taste
Add the coriander and allow to completely cool
Divide the filling once cool into golf ball sized balls
Remove the divided buns and flatten each one to form a disc and then a cup
Add a ball of filling in the center
Pull the edges together to seal
Bake for 10 mins in a preheated oven at 350 degrees
After that remove and brush with egg wash and sesame seeds
Bake for another 30 mins