1largebanana leafcut into 8 pieces of 10 x 10 cm or use parchment paper
Instructions
Steam the purple sweet potato (can be prepared the day before):
Peel and cut the sweet potato into small chunks. Steam over high heat for 5 minutes or until you can easily mash with a fork. Mash the potatoes with sugar while they are hot. You can use an immersion blender to make it smooth too. Mine wasn't mashed all that smooth and that's why you can see some purple dots. Let it cool down while you prepare other things
Oil the cut banana leaves with some cooking oil. You can use parchment paper too and you don't need to oil the parchment paper. Set aside.
Activate the yeast:
Put the yeast, water and sugar in a small bowl. Stir to combine and then let it sit for 10 minutes. The mixture will turn foamy and bloom. This shows that the yeast is active
Make the dough:
Cut sweet potatoes into small chunks and steam over medium-high heat until soft, about 10 minutes. Puree until smooth. Mash with sugar. When it is no longer hot and lukewarm, add the yeast mixture, and oil. Add glutinous rice flour, all-purpose flour, salt. Knead and gradually add a bit of water until you can form a rough dough. Cover and rest for 15 minutes. Then go back and knead into a soft and smooth dough
Shape the dough:
Divide the dough into 8 equal pieces. Oil both of your palms lightly (don't make it too greasy) and roll the dough into a smooth round ball and place it on the banana leaves and flatten it with your palm to form a disc. Repeat with the rest of the dough balls
Proof the dough:
Cover with a clean tea towel and put at a warm place to let them proof for at least 1 hour (no less). It may take longer than 1 hour in a colder climate. I found that if the dough is properly proofed, the hee pan will have fluffy with a slightly chewy texture. They will puff up to about 50% of its original size and feels really light. If you gently press with your finger, it will bounce back slowly
Steam:
Arrange the proofed buns inside the steamer. Start with a cold steamer that you have filled up with some water. Wrap the lid with towel to prevent condensation from dropping on the buns. If you use bamboo basket, you don't need to do this.
Turn the stove on and adjust the heat to medium. When the water comes to simmer, crack the lid open to allow some gap a bit to let steam escape. Start the timer and set it to 15 minutes and let them steam over medium heat with the lid slightly opened and DO NOT crank up the heat. When 15 minutes are up, allow 5 minutes before opening the lid
Remove the hee pan to let them cool on the cooling rack so the bottom won't get all wet and soggy. Serve them warm