Gently stir the yeast into the warm water until it has dissolved.
Place the flour, sugar, bicarbonate of soda and salt into a bowl and mix together. Add the warm water with yeast and mix together with a wooden spoon until it binds together.
Scrape the dough out onto a lightly floured surface and knead the dough for about 5 minutes until it has formed a smooth dough.
Roll into a ball, place in a bowl and cover with cling film. Leave in a warm place for 2 hours until it has doubled in size.
Tip the dough onto a floured surface and knead gently to knock the air out of it. Divide the dough into 8 evenly sized balls depending on how large you would like the buns. Roll each ball into equal oval shapes approximately 12cm in length. Brush the top side with a little oil and fold them over.
Steam the bao buns (in batches if required) in steamer baskets over boiling water for 18-20 minutes. They will be light to pick up when ready and have a lovely caramelised brown colour.
Fillings
Preheat the grill to medium-hot heat.
Lay out the bacon on a baking tray on greaseproof paper.
Mix together the maple syrup, miso paste and soy sauce and brush over the bacon on each side.
Place under the grill for 1-2 minutes each side until crispy.
Spread the inside of each bao bun with peanut butter and stuff 3 rashers of bacon in each. Drizzle with the chilli jam and serve whilst hot.