6 hr (mostly chilling the jelly), about 1 hr 15 min hands-on · About 32 dumplings, 4 people
Photo: Miya.m (CC BY-SA 2.0) via Wikimedia Commons · source
The soup inside is a jellied stock folded into the filling cold; it melts in the steamer. Make the jelly the day before and the rest is a long, happy afternoon of pleating.
For the jelly: 500 g pork skin or 4 pork trotters, split (or 2 chicken backs plus 3 tsp powdered gelatin)
1 thumb ginger, sliced
2 scallions
1 tbsp Shaoxing wine
1.2 liters (5 cups) water
For the filling: 450 g (1 lb) ground pork, at least 25% fat
1 tbsp light soy sauce
1 tsp dark soy sauce
1 tbsp Shaoxing wine
1 tsp sugar
3/4 tsp fine salt
1/4 tsp white pepper
1 tsp toasted sesame oil
2 tsp finely grated ginger
2 scallions, finely minced
For the dough: 300 g (2 1/2 cups) all-purpose flour, plus more for rolling
160 ml (2/3 cup) warm water
1/4 tsp salt
To serve: 4 tbsp Chinkiang black vinegar, a matchstick pile of fresh ginger, napa cabbage leaves for lining the steamer
How to make it
Make the jelly (the day before, 3 hr): Blanch the pork skin or trotters in boiling water 5 minutes, drain and rinse. Put them back in a clean pot with the ginger, scallions, wine and 1.2 liters water. Simmer, uncovered, very gently for 2 1/2 to 3 hours until reduced to about 400 ml (1 2/3 cups). Strain, season lightly with salt, pour into a shallow dish and chill until firm, at least 4 hours or overnight. (With chicken backs: simmer 2 hours, strain 400 ml, and whisk in the gelatin while hot.)
Make the filling (10 min): Stir the pork with both soy sauces, wine, sugar, salt, pepper, sesame oil and ginger in one direction with chopsticks for 2 to 3 minutes until it turns sticky and pale. Dice 250 g (about 1 1/2 cups) of the jelly into 5 mm cubes and fold it in with the scallions. Chill 30 minutes; cold filling is far easier to wrap.
Make the dough (15 min, plus 30 min rest): Mix flour and salt, pour in the warm water and stir into shaggy crumbs, then knead 8 to 10 minutes until smooth and soft, like an earlobe. Cover and rest 30 minutes.
Roll the wrappers (20 min): Roll the dough into a rope 2.5 cm (1 in) thick and cut 32 pieces of about 14 g each. Flatten each with your palm, then roll into an 8 cm (3 1/4 in) circle, thinner at the edge than in the middle: roll from the edge toward the center, turn a little, repeat. Keep the rest covered.
Pleat (30 min): Put a heaping tablespoon (about 20 g) of filling in the center. Holding the wrapper in one hand, use the other thumb and forefinger to make small pleats around the edge, turning as you go, about 16 to 18 pleats, then twist the top shut. If a wrapper tears, start again; a hole means no soup.
Steam (8 min): Line a bamboo steamer with cabbage leaves or perforated parchment. Set the dumplings 2.5 cm apart. Steam over a wok of rapidly boiling water for 8 minutes, until the skins look translucent and the dumplings slump slightly.
Serve (right away): Mix the vinegar and ginger in small dishes. Lift each dumpling by the knot into a soup spoon, bite a small hole, sip the soup, then eat the rest with a dab of vinegar and ginger.
Tips
The jelly is the soup: if it doesn't set firm in the fridge, simmer it down further.
Freeze extra dumplings on a floured tray, then bag them; steam from frozen for 12 minutes.
The thick center of the wrapper is what holds the soup; keep the middle twice as thick as the edge.