Dough:
1/2 c glutenous rice flour
1 T sugar
1/4 c water
Just mix everything together until it no longer sticks to your hands (give it a minute, it will turn to a playdough consistency after you work it a bit). Then make little balls in the palm of your hand (~1" in diameter) and flatten it out, put your filling (red bean paste, black sesame paste, peanut butter, etc.) in the center and pinch the dough back over the filling. Then gently roll in the palm of your hand to get perfectly round again. You can then freeze them or put them in boiling water until they float for 1 minute (should take around 6 minutes total).
I made the big red bean ones, and had some frozen store-bought black sesame paste balls that I added to the pot.