I made the same mistake I made last year, bought the wrong rice flour. The dough made from normal rice flour is much harder, and couldn't get cooked even boiled for a long time, it looked cooked outside, but raw inside.
Only around 10:15pm last night I realised I made this mistake again. And quickly we went to the nearest supermarket when they were closing, but they had their glutinous rice flour sold out. We then went to an indian grocery shop and fortunately they still have a few packets left. To make it more dramatic, it started raining when we stepped out of the house.
I do not have a particular recipe for this. I mix the flour and water gradually to get the desired dough texture (Firm enough to roll and do not stick). Add and mix in coloring when needed. Roll the dough into small balls. Cover them with cling paper (to avoid losing moisture from the dough balls) and keep them in the refrigerator for the next-day's use.
Today is Winter Solstice Festival, 冬至. Chinese celebrate it, family members gather togather and eat Tang Yuan, symbolizes reunion.
In the morning, I boiled the Tang Yuan in a pot. When the Tang Yuan floats onto the surface of the water it means it's cooked. I scooped the cooked Tang Yuan and into a bowl of cool water to avoid them from sticking to each other.
I used Gula Melaka (coconut sugar), boiled in water, made the dessert soup to eat with the Tang Yuan. Too bad I did not prepare some Pandan leaves to go with it, if not it will be more fragrant. Again, no complicated recipe, just boil a small pot of water, stir in the Gula Melaka bit by bit until I get the desired sweetness.