To activate the yeast:
10 grams instant yeast,2 tsp sugar,4 Tbsp warm water (not hot).
Dry ingredients for the dough:
130 grams cornflour, plus more for dusting as needed
130 grams potato starch,90 grams glutinous rice flour
100 grams rice flour,2 tsp baking powder
1/2 tsp salt,60 grams sugar
Wet ingredients for the dough:
260 ml of water
60 ml of cooking oil
Activate the yeast:
Put all ingredients in the bowl and stir to mix. Let it sits for 10 minutes. The mixture should be foamy and bubbly, which indicates that the yeast is still active. If it doesn't after 10 minutes, the yeast is no longer working and you need to get a new one before proceeding with the recipe
Prepare the dough:
Stir all the dry ingredients in a large mixing bowl to mix them up. Then add the water and oil and stir to roughly mix. Use one of your clean hands to knead it into a dough. The dough should feel a bit wet and moist but not sticky to your fingers. If the dough feels dry, cracking, and falls apart, add a bit more liquid, a teaspoon at a time until it comes together. It should feel like a "playdoh". The dough doesn't have any elasticity
First proofing :
Cover and put the dough in a warm place. It took a bit over 1 hour for the dough to double in size. Don't go on time. It may be faster or longer depending on the temperature
Shape and fill the dough:
Scoop the proofed dough out onto a working surface, lightly dusted with cornflour. Use your clean hands to gather the dough back into one large dough and then divide into 8 equal portions. Keep them covered and work with one dough at a time
Prepare a small cup of water next to you in case you need it to help you shape the dough. Roll the dough flat, place blueberries and gently mould the dough to seal the filling. If at any point the dough feels dry and crackly, dab the dough with a bit of water and then roll it into a smooth round ball. Place this on parchment paper and cover it with a damp towel. Repeat with the rest of the dough balls.
Place the shaped buns at a warm place again to let them proof until they are about 50% of their original size (they won't double in size). This round will be faster, about15-30 minutes, but please don't go on time. The dough needs to feel somewhat lighter when you lift them up and about 50% puffy
Get the steamer ready by bringing the water in the steamer to a rolling boil. Place the shaped buns inside a steaming basket or on a steaming rack. If you have a 3-tiered steamer, you can steam them all at once. Otherwise, you need to steam in batches. Lower the heat to medium and let the buns steamed for 8 minutes. After 8 minutes, turn off the heat and wait for 1 minute before opening the lid
Remove the steamed buns from the steamer and place them on a cooling rack. They are the best fresh.