Take out a flat-bottomed pan and keep the stove dry. Add a small amount of cooking oil to the pan, enough to cover the bottom in a thin, even layer. Place the frozen dumplings directly from the freezer into the pan, arranging them neatly and leaving space between each dumpling to avoid sticking during cooking. Heat on low and cover the pan with a lid.

In a small bowl, add 7g of cornstarch, then slowly pour in 110g of water while stirring with chopsticks or a small spoon until the cornstarch is fully dissolved and forms a smooth, lump-free mixture. Set aside.

Keep the heat on low to allow the dumplings to cook slowly. Occasionally, check the bottom of the dumplings. When the bottoms turn a golden, crispy color, this indicates they are ready for the next step. Slowly pour the prepared cornstarch water around the edges of the pan. The cornstarch water will quickly spread across the pan.

After adding the cornstarch water, turn the heat to medium-low and cover the pan. This will allow the dumplings to cook through more quickly with the steam, while the cornstarch water thickens. Open the lid from time to time to check. When the water is almost gone and the cornstarch forms a thin, crispy, slightly golden layer around the dumplings, they are nearly done.

Open the lid, and evenly sprinkle toasted sesame and chopped green onions over the dumplings. Once sprinkled, carefully use a spatula to remove the dumplings from the pan and plate them.