In a bowl, combine glutinous rice flour, corn starch, white sugar, corn oil, and milk.
Stir with a whisk until well mixed.
Sieve the mixture into another container and cover it with plastic wrap. Make holes in the plastic wrap.
Steam it for 20 minutes.
After steaming, add butter and knead the mixture thoroughly. Knead and stretch the dough. It should be strong enough not to break when stretched.
Take a small piece of the dough by squeezing it out from your thumb and forefinger, forming a small ball.
Make the dough into a flat circular wrapper, but still thick enough to hold the red bean paste.
Place the red bean paste in the center and wrap it by sealing the edges.
Coat it with coconut flakes or shredded coconut.