Bloom gelatin in 1/2 cup cold broth for 5 minutes.
Simmer 2 cups broth with 2 1/2 tbsp gochujang, 1 tbsp soy sauce, and sugar. Whisk smooth.
Stir in 1/2 cup heavy cream. Heat gently for one minute.
Whisk in bloomed gelatin to dissolve. Pour into a shallow dish. Chill until firm.
Combine remaining 1/4 cup broth, 1/4 cup cream, 1/2 tbsp gochujang, 1/2 tbsp soy, sesame oil, and vinegar. Chill.
Mix pork, scallions, ginger, garlic, wine, remaining 1/2 tbsp soy, 1 tsp sesame oil, salt, and white pepper until tacky.
Dice the set gel into 1/4-inch cubes. Fold half into the pork mixture. Keep the rest chilled.
Set up a steamer with water. Line basket with cabbage leaves and brush with oil.
Place a wrapper in your palm. Add 1 tbsp filling and a few gel cubes. Pleat and pinch closed.
Steam dumplings over boiling water until translucent and cooked through, 8–10 minutes per batch.
Warm the chilled sauce gently until steamy; do not boil. Spoon a little into serving bowls.
Set dumplings over the sauce. Splash with black vinegar and serve hot.