Core and finely chop the Napa Cabbage, sprinkle it with Salt and let it sit for 10–15 minutes to draw out excess moisture; then rinse and squeeze the cabbage dry in batches, reserving the liquid if desired.
Drain and press the Firm Tofu between paper towels or a clean cloth to remove excess water, then crumble it into small pieces.
Soak the Glass Noodles in warm Water until softened (about 10 minutes), drain and cut them into short, manageable lengths with scissors.
Finely chop the Garlic Chives and Scallions, and mince the Garlic and Ginger.
In a large bowl combine the Ground Pork, crumbled tofu, squeezed cabbage, chopped glass noodles, chives, scallions, garlic and ginger; season with Soy Sauce, Sesame Oil, Sugar, freshly ground Ground Black Pepper and mix well.
Beat in the Egg to help bind the filling and mix until the filling is cohesive and slightly sticky; taste and adjust seasoning (be careful with extra salt because of the soy).
Lay out the Round Dumpling Wrappers and keep them covered with a damp towel. Place about 1 tablespoon (adjust to wrapper size) of filling in the center of each wrapper, moisten the rim with a little Water, fold and pleat or press to seal tightly.
Heat a nonstick skillet over medium-high and add a thin layer of Neutral Oil. Arrange the dumplings flat in the pan and cook until the bottoms are golden, about 2–3 minutes.
Carefully add about 1/3 cup of Water to the pan (enough to create steam), cover immediately, and steam the dumplings until the filling is cooked through, about 5–7 minutes. Remove the lid and continue cooking a minute longer to crisp the bottoms again.
For the dipping sauce, whisk together additional Soy Sauce with Rice Vinegar, a drizzle of Sesame Oil, a pinch of Gochugaru and a little Sugar to taste; finish with toasted Toasted Sesame Seeds and sliced scallion.
Serve the mandu hot straight from the pan with the dipping sauce alongside—crispy, steamy dumplings are best enjoyed immediately.
