Bring chicken broth to a boil in a 3-5 quart saucepan. Add the agar agar all at once, sprinkling across the surface of the chicken broth (careful--the chicken broth will foam up), and whisk for 2 minutes until the agar agar is dissolved. Pour broth mixture into a shallow container and set aside to cool for 2 hours or until solid. When solid, dump gelatinized broth onto a cutting board and dice finely. Set aside.

Place flour in bowl and create a well in the center. Pour in boiling water and carefully stir until a rough dough forms. Let cool for at least 5 minutes. Knead in bowl, adding at least 2 additional tablespoons of flour (and more, as the dough requires) until dough is no longer sticky. Place dough in clean bowl, cover with plastic wrap, and let rest for at least 30 minutes.

Place cabbage and salt in food processor and pulse until finely chopped, about 10 one-second pulses. Transfer to a fine-meshed strainer set over a bowl. Allow to rest for 30 minutes. Meanwhile, place scallions, pork, soy sauce, Shaoxing wine, and sugar in bowl of food processor. Pulse until homogeneous and pasty, about 10 one-second pulses. Transfer to a large bowl and stir in diced Gelatinized Broth. Set aside.

After cabbage has purged, squeeze any remaining moisture out with your fingers, then transfer to the bowl with the pork. Fold together with a spatula until homogeneous. Microwave a small ball of the filling in a bowl for 10 seconds and eat it to taste for seasoning. Add more salt, soy sauce, or sugar as necessary and repeat tasting/seasoning step until the filling tastes like you want it to. Refrigerate until ready to use.

Divide dough into 4 sections, and each section into 8 small tablespoon-sized balls, making 32 balls total. On a well-floured work surface, roll each ball into a round 3 1/2- to 4-inches in diameter. Do not hesitate to add more flour to the dough if it becomes sticky. When rolling, try to keep the wrappers thinner on the edges and thicker in the center (otherwise, they will be too thick on the edges after wrapping). The wrappers will be about 1/16-inch thick on the edges, and 1/8-inch thick in the center. Dust front and back of rolled wrapper with more flour. Ideally, you would wrap as you go (a helper to wrap the dumplings would work well here), but alternatively you can stack the wrappers and keep under plastic until all of them are rolled out.

To form dumplings, place 1 tablespoon of filling in the center of a wrapper. Moisten the edges of the wrapper with a wet fingertip. (Wetting the dough may not be necessary if the homemade wrapper is still sticky, but check the strength of your dumpling seams to make absolutely sure that the seams stay closed.) Fold in half and pinch the center seam closed. Pleat the front edge of the wrapper repeatedly, pinching the edge closed after each pleat until the entire dumpling is sealed. Again, make sure you check the seams--the dumpling should be so tightly pinched that it looks almost like you've merged the dough into one. Transfer sealed dumplings to a well-floured wooden or parchment-lined board.

Combine all sauce ingredients in a small bowl and set aside at room temperature.

Bring a large pot of water to a boil. Add a 6 to 12 dumplings and boil until they float (About 1 minute). Continue boiling for 2 minutes longer, then transfer to a plate with a wire-mesh spider or slotted spoon. Heat 3 tablespoons vegetable oil in a 10-inch nonstick skillet or the bottom of a well-seasoned cast iron wok over medium heat until shimmering. Add dumplings flat-side down and cook, swirling occasionally, until bottom of dumplings are golden brown and crisp. Serve immediately with dipping sauce. Repeat step 7 with remaining dumplings, working in batches.