Combine flour and salt in a large bowl. Pour the boiling water over the flour mixture and stir with a fork until it begins to come together, then add cold water gradually until you have a shaggy dough. Knead the dough for 8-10 minutes on a lightly floured surface until smooth and elastic—this develops the gluten for tender, chewy wrappers. Cover with a damp cloth and let rest for 20 minutes while you prepare the filling. I always use King Arthur all-purpose flour because it gives the dough better elasticity and texture.

Toss the shredded cabbage with 1/2 tsp salt and let it sit for 10 minutes to soften and release moisture. While the cabbage rests, finely dice the corned beef into 1/4-inch cubes and pulse together with ginger, parsley, white pepper, soy sauce, rice wine, and sesame oil in a food processor until well combined but still textured. After 10 minutes, squeeze the cabbage firmly to remove excess water, then fold it into the meat mixture along with garlic powder. The salting and squeezing step removes excess moisture that would make the dumplings soggy during cooking.

Divide the rested dough into 16-20 equal pieces and roll each into a 3-inch round wrapper with a rolling pin, making the edges slightly thinner than the center. Whisk together cornstarch and water to create a slurry for sealing. Place about 1 tablespoon of filling from Step 2 in the center of each wrapper, wet the edges with the cornstarch slurry, fold in half to create a half-moon, and press firmly to seal—make sure there are no air pockets.

Heat 2 tablespoons sesame oil in a large skillet over medium-high heat until shimmering. Arrange the dumplings flat-side down in the pan in a single layer (work in batches if needed) and cook undisturbed for 3-4 minutes until the bottoms are golden brown and crispy. Pour 1/2 cup water around the dumplings (not directly on top), immediately cover the pan with a lid, and reduce heat to medium. Steam for 6-8 minutes until the water is absorbed and the wrappers are tender. I prefer Kadoya brand sesame oil for its deep toasted aroma that adds complexity to the crispy bottoms.

While the dumplings steam, whisk together sesame oil, sliced scallions, rice vinegar, and soy sauce in a small bowl to create a bright, tangy dipping sauce. Once the dumplings are cooked and the pan is dry, transfer them to a serving plate and serve immediately with the dipping sauce on the side. I use Marukan seasoned rice vinegar because it has the perfect balance of sweet and tangy without requiring extra sugar.