Heat stock until warm (do not boil).
Sprinkle gelatin over stock, stir until dissolved.
Refrigerate 1–2 hours until set, then chop into small cubes.
Mix flour, salt, and warm water until a shaggy dough forms.
Knead 8–10 minutes until smooth. Cover, rest 30 minutes.
Combine pork, soy sauce, ginger, wine, sugar, and pepper. Mix vigorously.
Fold in green onions, sesame oil, and chopped aspic. Chill 15 minutes.
Roll dough into a log, cut into 16 pieces. Roll each into a thin 3.5" circle.
Add 1 tbsp filling to center. Pleat edges, sealing tightly (leave small hole on top).
Line steamer with parchment, place dumplings 1" apart.
Steam 8–10 mins over boiling water. Serve immediately with black vinegar + ginger.
