Put water, ginger and sugar in a saucepan. Bring to a boil and then lower the heat, cover with a lid and let it gently simmer for 15 minutes. Turn off the heat. Remove the ginger. Add osmanthus flower and simmer for another 5 minutes and then turn off the heat
Prepare tang yuan:
Mix glutinous rice flour and icing sugar in a mixing bowl. Add the boiling hot water (make sure it's REALLY hot!). Stir to mix with a spatula at first and when it's not too hot anymore, use a clean hand to mix and knead into a non-sticky dough. Add a bit of water as needed to form a dough. The dough will be soft and pliable because of the hot water. Add food coloring if you want to and knead until the color is even. Cover them with plastic wrap to prevent it from drying out
Pinch off a small amount of dough, about 8-10 grams (it's up to you how big or small you want them to be) and then roll into small balls. You should have no problem with the dough breaking because the dough is so soft and pliable. Keep the small balls covered with plastic wrap too. Continue with the rest
Cook the tang yuan:
Bring a small pot of water to a boil. When they are rolling boil, add the tang yuan balls and cook until they float to the top. Once they float to the top, cook for another 1 minute. Use a slotted spoon to remove them from the pot and submerge them in a fresh water briefly to stop the cooking process and to prevent them from sticking to each other
To serve:
Portion out tang yuan into bowls and ladle the osmanthus broth over and serve immediately
If serving with osmanthus syrup:
If you don't want to prepare the osmanthus ginger broth and you have store-bought osmanthus syrup (or osmanthus honey), you can serve the tang yuan with osmanthus syrup/honey instead