1. In a large mixing bowl, add the glutinous flour.
2. In another bowl, dissolve the brown sugar in warm water and pour it little by little onto the flour. Combine it slowly into a nice sticky dough. Set aside.
3. In a bowl, spoon out the insides of the sweet potatoes.
4. Add in the light brown sugar and rice milk. Mash with a potato masher and then mix until well combined.
5. To fill the dough with the sweet potato, make sure to use floured hands when removing a small ball of about a 1 tablespoon piece size of the dough.
6. Place this ball in one palm and using the knuckle of the other hand make indents in the middle of the dough.
7. Pinch the outer sides of the dough so that it is thinner than the middle. Take 1 teaspoon of the sweet potato filling and place in the center of this dough.
8. Gently pinch the dough together on the sides above the filling, and enclose the filling so that there are no cracks. Roll this dough into a ball and set aside.
9. In a small plate, pour out the black sesame seeds and take each ball and roll it around the seeds until it is well coated. Repeat this process until all balls are filled and coated.
10. In a saucepan over medium high, heat approx. 2 1/2 inches of sunflower oil to 350 degrees F (175 degrees C) for frying the balls.
11. Gently drop each of the balls into the oil and cook for approx. 5 minutes, until they look light golden brown.
12. Once the balls are fried place them on paper towels to drain excess oil.
13. Serve the black bean sesame seeds with tea or warm milk.