First make the yeast mixture. Combine the yeast and water in a bowl, stir and set aside.
Make the Tangzhong mixture. Place the Milk Water and Plain Flour in a saucepan, heat over a medium heat until thickened, take off the heat and stir until a thick paste forms. Place the paste on a plate and set aside to cool.
Make the Dough. Get the yeast mixture, and add the Flour, Milk, Sugar, Salt, Egg & Tangzhong mixture, stir together. If the dough looks too wet, add sprinkles of flour until workable.
Add 15g of the butter at a time, kneading in-between until it is completely absorbed by the dough ( This process is easiest with a mixer with a dough hook, but can still be done by hand, be warned it will get messy! add sprinkles of flour to help with the stickiness)
Form the dough into a ball, place in a greased or lined bowl, cover with cling film, allow to rise for 1 hour.
Divide the dough into 8 pieces, form 8 balls (see video)-I used 7 dough balls due to my oval dish, but 8 should be sufficient for a round tin.
In a lined or greased deep edged dish or cake tin, arrange the dough balls (see video) Cover with cling film, allow to puff up for 30-45 minutes.
Preheat the oven to 170°c
Make the Egg wash by mixing the water and egg together
Brush the Egg wash on the buns.
Pop in The Oven for 20-25 minutes until golden