Prepare the main sauce: Mix equal parts of oyster sauce, soy sauce, and white sugar until well combined.
Prepare water chestnuts: Dice the water chestnuts for crunch.
Prepare shrimp: Cut shrimp into chunky pieces.
Prepare pork filling: Blend pork and pork fat in a food processor until rough paste.
Make sambler paste: Blend cilantro root, garlic, and white pepper in a food processor.
Combine filling ingredients: Mix pork paste with sambler, sesame oil, white pepper, egg, cornstarch, scallions, shrimp, and water chestnuts.
Chill filling: Refrigerate filling for 15 to 30 minutes.
Prepare dipping sauce: Roast chilies until charred, then blend with white vinegar and sweet soy sauce.
Wrap dumplings: Use wonton wrappers to scoop and fold filling, ensuring edges are sealed.
Steam dumplings: Steam dumplings for 13 to 15 minutes.
Serve: Plate dumplings and drizzle with garlic oil, serve with dipping sauce.