Boil or steam the sweet potatoes until soft enough to pierce with a fork
Place them in a large bowl and mash with a fork
Add glutinous rice flour, matcha powder and water and mix well – it should form a sticky paste-like mixture that’s easily moulded into balls (add a tiny bit more water if necessary, but be careful not to add too much)
Mould the mixture into small balls
Bring a large pan of water to the boil and add about a handful of the balls once the water’s boiled, leaving the pan on high heat throughout – it’s very important to wait until the water’s boiling and you mustn’t add too many at a time otherwise the temperature of the water will drop and they won’t cook properly!
Cook the balls in a few batches – they’ll be ready 1-2 minutes after they’ve risen to the surface of the water
Scoop them out with a spoon once they’re done and transfer to a bowl filled with cold water. Repeat this process until all the balls are cooked
Leave them in the cold water for a couple of minutes, then transfer them to a dry bowl or plate
Best eaten immediately, but leftovers can be kept in an airtight container in the fridge for up to a few days
For the red bean paste:
If using dried adzuki beans, soak and cook them according to instructions on packet
If using tinned adzuki beans, drain and rinse them
Add prepared adzuki beans to a saucepan with the sugar and enough water to cover
Bring to the boil and cook for about 15 minutes on a low heat
Use a food processor or hand-held blender to blend the paste to your desired consistency - you can leave the texture a little chunky if you prefer, and add more sugar to taste if you wish
Notes
*You can use store-bought red bean paste and skip this step