Step 1

Toss cubes of pork and salt in a medium bowl. Spread the pork pieces on a rimmed baking sheet, leaving space between the pieces than place in the freezer for 15 minutes until just starting to freeze, but still pliable.

Step 2

In bowl of food processor, combine salted pork, bacon, egg, stock, soy sauce, and sugar. Process until a rough puree is formed and pieces of pork are no larger than 1/8th of an inch, about 20 seconds. Add leeks to food processor and pulse until evenly incorporated, about 6 one-second pulses.

Step 3

Working with a few skins at a time, place approximately 1 tablespoon of filling in the center of each wrapper. Use your finger to spread a small amount of water around the edge of each wrapper. Seal wrappers by folding in half and pleating one side 5 or 6 times, pinching the edges together as you go. Place finished dumplings on a parchment-lined baking sheet, separating them to avoid sticking, and covering the whole thing with a clean, damp washcloth.

Step 4

Line a bamboo steamer with wilted cabbage or lettuce leaves, or create a parchment liner. Place dumplings in steamer, leaving a small gap between each one a place over a wok of simmering water. Steam for 7 to 9 minutes until skins are translucent and filling is cooked through. Serve immediately with soy sauce, chili paste, Chinkiang vinegar, black vinegar, or plain rice vinegar.