1) MAKE THE RED BEAN FILLING: In a medium bowl, combine the red beans with 1 cup (240 ml) of water. Cover with plastic wrap and soak overnight.
2) Drain the red beans, then transfer to a small saucepan with the remaining 3 cups (720 ml) of water. Bring to a boil over medium-high heat, then cover and cook for 1 hour, until soft enough to mash with a fork.
3) Add the sugar and cook, stirring frequently, until the liquid evaporates and a thick red bean paste forms.
4) Transfer the red bean paste to a bowl. Cover with plastic wrap, pressing it directly onto the surface of the paste to prevent a skin from forming. Refrigerate until ready to use.
5) MAKE THE DOUGH: In a liquid measuring cup or small bowl, whisk the hot water with the light brown sugar until the sugar dissolves.
6) Add the glutinous rice flour to a medium bowl and use a spoon to create a small well in the center.
7) Pour the sugar syrup into the well and stir for 5 minutes, until the dough is well combined and no longer sticks to the bowl.
8) Lightly dust a clean surface with glutinous rice flour. Turn the dough out and knead for 5 minutes, until it forms a smooth, round ball. Use a little bit more flour or water as needed.
9) Divide the dough into 8 pieces. Roll the pieces into small balls, then flatten into discs about ½ - inch thick and 2½- inches in diameter.
10) Place 1 tsp. of red bean filling in the center of a piece of dough. Fold in the edges to cover the filling, then roll into a ball. Roll the ball in the sesame seeds until the dough is covered. Repeats with remaining ingredients.
11) Heat the vegetable oil in a large pot until it reaches 350ºF.
12) Fry the sesame balls for 15 minutes, stirring frequently, until golden brown. Transfer to a wire rack set over a baking sheet to drain and let cool 15 minutes before serving.