Warm the rice milk in a small pot for around 2 minutes, then turn off the heat. Add in agave syrup and vanilla extract and mix well.
In a large mixing bowl, sift in all the dry ingredients, whisk and mix well.
Add the butter into the dry ingredients mixture and rub the cold butter into the flour until well combined.
Make a well in the middle of the large mixing bowl and gradually pour 250ml of the warm rice milk mixture into the well. Use a spatula to mix the dry and wet ingredients together.
Then add in the rest of the 50ml rice milk mixture gradually as you use your hands to knead the dough until you have a smooth dough that is slightly sticky.
Cover the dough with cling wrap and rest on the benchtop for 30 minutes.
For stuffing the dough:
Dust the work surface with some gluten free all purpose flour.
Divide the dough equally into 26 round balls around 55g (2oz) each.
Flatten each ball into a disc or patty and shape each patty into 3 inch round dough with the middle thicker than the edges.
Scoop and place 1 teaspoon of red bean paste onto the middle of each dough, wrap and pinch the dough together with small amount of water and shape into a smooth ball again.
Using your fingers, gently flatten the ball into a patty. Hold and rotate the patty as you press gently with your fingers until the patty is around 3 inch wide and 1cm in thickness.
Dust with some gluten free all purpose flour and place on a large tray.
Wet the surface of each dough with some water and sprinkle generously with some white sesame seeds. Press the white sesame seed onto the dough with your fingers.
For cooking the doughnuts:
Heat up a wok half filled with rice bran oil. Deep fry each doughnut for 1 to 2 minutes on each side on low to medium heat or until golden brown. Cook the doughnuts in batches.
Remove and drain the cooked doughnuts on kitchen paper towel.
Reheat by covering the doughnuts with aluminium paper and bake in the oven for 5 minutes or in microwave for 40 seconds or until doughnuts are soft.