Step 1

Place 1/2 cup unhusked dried green mung beans in a medium bowl and add enough cool water to cover by a few inches. Let soak uncovered at room temperature overnight.

Step 2

Drain and rinse beans. Place in a small saucepan and add enough cool water to cover (about 1 cup). Bring to a boil over high heat. Reduce the heat to medium and simmer until the water is almost totally boiled off, stirring at the end to make sure beans aren’t sticking to the bottom, about 15 minutes. Skim off any foamy scum that rises as the beans cook.

Step 3

Drain the beans. Transfer to a food processor fitted with the blade attachment and add 1/3 cup granulated sugar. Turn the motor on and drizzle in in 2 tablespoons neutral oil and 3 tablespoons of the water. Continue to process until a thick paste forms, adding up to 2 more tablespoons of water and scraping down the sides as needed, about 2 minutes. Transfer to a bowl. Cover and refrigerate for at least 20 minutes or up to 2 days to make it easier to shape.

Step 4

Place 1/2 cup black sesame seeds in a large skillet over medium-low heat and toast, tossing occasionally, until fragrant, about 5 minutes. (Alternatively, toast for about 4 minutes in a 400°F oven or toaster oven.) Transfer to a food processor fitted with the blade attachment. Add 1/3 cup black sugar, 1 tablespoon water, and 1 tablespoon toasted sesame oil. Process until a very thick paste forms, stopping and scraping down the sides as needed. Transfer to a bowl. Cover and refrigerate for at least 20 minutes or up to 2 days to make it easier to shape.

Step 5

Place 2/3 cup water and 2 tablespoons granulated sugar in a small saucepan. Bring to a boil over medium heat to make the syrup. Meanwhile, place 1 cup plus 2 tablespoons sticky rice flour in a large bowl.

Step 6

Immediately pour the syrup into the rice flour. Using a rubber spatula, mix until a smooth dough forms — the dough should get stickier and stickier as you work with it. Form the dough into a ball with a rubber spatula or bench scraper and spoon 1 tablespoon neutral oil over it, covering all exposed surfaces. Cover the bowl in plastic wrap and let the dough rest at room temperature for 30 minutes.

Step 7

Spoon out 1 level tablespoon filling (about 15 grams) and roll between your palms to form a firm ball. If the filling is too dry, mix in a spoonful of hot water into the filling before trying again. Repeat until you have 10 balls (you will have leftover filling).

Step 8

Place 1/3 cup hot water and 1 tablespoon sticky rice flour in a separate bowl and whisk until a sticky paste forms. This is the “glue” for your sesame seeds. Pour 1/2 cup raw white sesame seeds into a shallow plate.

Step 9

Uncover the dough and touch with your hands: it should be much firmer and less sticky than before resting. Ideally, it should feel like fresh Play-Doh — pliable, but keeps its shape with no cracking. If it’s too hard or cracking, mix in a tiny bit of boiling water. If too soft and sticky, add a bit more rice flour. Working quickly, briefly knead the dough just to incorporate any residual oil, then divide it into 10 portions (about 1 1/2 tablespoons or 28 to 29 grams each). Cover the portions with plastic wrap.

Step 10

Fill the sesame balls: Lightly oil your hands. Roll 1 portion of the dough between your palms to form a smooth ball, then flatten into a disk about 3 inches wide and 1/4-inch-thick. Wrap the disk around a filling ball, making sure there are no air pockets, and smoosh the edges together so the filling is completely sealed inside. Roll the ball between your palms until smooth and place on a plate or baking sheet. Repeat with the remaining fillign and dough balls, re-oiling your palms as needed. The dough should be very pliable, but if it’s sticking to your oiled hands, add a little more flour.

Step 11

Pour enough neutral oil into a wok, large high-sided sauté pan, or Dutch oven to nearly submerge a dough ball. (In a 14-inch wok or 5 1/2-quart Dutch oven, this is almost 8 cups oil.) Heat on high heat until 300°F. Meanwhile, fit a wire rack over a baking sheet. Brush each ball with the sticky rice paste, then roll in the sesame seeds until completely coated and return to the plate or baking sheet.

Step 12

When oil is ready, turn off the heat. Gently roll all the dough balls down the sides of the wok (or lower the balls with a spider into the oil). The dough balls should be emitting very tiny bubbles as they acclimate to the oil, about 3 minutes. After a couple of minutes, the oil temperature will drop to about 250°F and the bubbles should slow. At this point, turn the heat on to medium-low.

Step 13

Use wooden chopsticks or a spatula to gently move the balls around as they begin to fry. For the next 5 minutes or so, they will gradually expand and float as the water in the dough evaporates, and it’s very important to make sure the oil temperature stays below 300°F. It’s during this stage that your sesame balls may crack and leak — even if you did everything right! Sometimes it just happens, and if it does, use a strainer to scoop out any leaked filling immediately, as it can ruin your frying oil.

Step 14

Once the balls are fully floating, turn the heat to medium and use the underside of a skimmer or chopsticks to roll the balls around the pan in one direction — this ensures even cooking and that they each have a perfectly round shape. Continue frying the balls this way for at least another 5 minutes. The oil temperature should not exceed 320°F during this time. Continue cooking until the balls are golden-brown, about 7 minutes. Use a skimmer or slotted spoon to transfer the sesame balls to a wire rack. Let cool for at least 5 minutes before serving warm.