Using a small pan, roast the sesame seeds until fragrant for about 5-7 minutes on low heat. Stir it constantly so that it does not burn! Remove from heat.
Using a food processor/ blender blend the sesame seeds, coconut sugar, and butter together until combined. Put into the fridge for about 15 minutes so that it's easier to work with. Once cooled, remove from fridge and roll into balls about 1.5 cm long (7g). It will make about 18-20 pieces.
Tang Yuan
In a separate bowl, mix together the glutinous rice flour with the hot water. Mix and knead until it turns into a dough. If it's too "wet" add in 5g of glutinous rice flour at a time until it's not longer sticky. If it's too "dry" add in 5g of hot water until it's smooth. Roll onto a dusted surface into a long log and cut into pieces. Roll each piece out (10g), flatten the piece out, and insert the sesame ball inside. Carefully pinch the glutinous rice sides and roll together into a ball. Freeze until ready to cook.
Ginger Syrup
In a small pot, heat up 2 cups of water with the ginger and rock sugar. Simmer until the rock sugar completely dissolves ~10 minutes.
Cooking the Tang Yuan
In a separate small pot, heat up 5-6 cups of water. Once boiled carefully insert your tang yuan inside and cook for 5-7 minutes until they float. Remove with a slotted spoon and serve with your ginger syrup. Enjoy!
Notes
You can freeze the Tang Yuan up to 6 months in your freezer.