In a large bowl, mix glutinous rice flour with water. Knead several minutes to form dough. And then take a small portion; shape the portion into a small around ball (size should be similar to litter finger top). Or you can firstly take one third out and shape it into a thin long log for an equal segmentation. Anyway, use the most comfort way to make small around balls.
To cook the balls, bring water to boil in a large pot. Cook until the sticky rice balls floating on the surface and then continue cooking for 30 seconds.
Transfer them out and soak in iced water until completely cooled down (to make them more elastic). And then drain.
Put 2/3 of the mango cubes and banana in your blender and add coconut milk(I do not list a specific amount because I cannot define the size of the mango, So adjust it according to your own experience. Blend until smooth.
Lay the smoothie firstly and then add mango cubes and sticky rice balls. Enjoy!
Notes
If you make too many small sticky rice balls, coat them with extra sticky rice flour and freeze.