Form the dough into a cylindrical log and cut into uniform portions. Using the palm of hands, roll each portion into 2-inch size balls. Continue to roll until the ball is smooth and without cracks.
Place the dough balls in a single layer on a platter and repeat with the remaining dough. Cover with plastic film until ready to use.
Using your thumb, make an indentation in the center of the dough ball and slowly enlarge to fit in a mung bean ball filling,
Place one tablespoon mung bean filling in the center and gather edges of dough around the filling.
Pinch dough together to completely seal and using the palm of hands, roll repeatedly into a smooth ball with no cracks or thin spots.
Place sesame seeds in a fine-mesh sieve and rinse in cold, running water until completely soaked. Drain well until moist but not dripping wet.
Spread the moistened sesame seeds on a flat dish.
Gently the prepared balls in the sesame seeds until fully coated and with no bare spots, pressing lightly to make sure seeds adhere well. Repeat with remaining dough and filling.