Peel and devein the shrimp, saving the heads. Heat 3 tablespoons of neutral oil in a small pan over low heat. Add the shrimp heads and cook slowly, stirring occasionally, until the oil turns a bright red and the shells become slightly crispy. Strain the oil and discard the heads.
In a large bowl, combine chopped shrimp, ground pork, ginger, soy sauce, oyster sauce, salt, cornstarch, egg, water, and the prepared shrimp oil. Mix in one direction until the mixture becomes sticky and cohesive. This helps the filling bind together and gives it a smooth texture.
Add the green onion at the end to keep its freshness, preventing it from turning mushy or developing an unpleasant onion flavor.
Transfer the filling to a piping bag or zip-top bag with a cut corner for easy filling. Pipe a small amount of filling onto each wonton wrapper. Pinch the wrapper to seal. Repeat until all filling is used.
In a small heatproof bowl, combine chili flakes, Sichuan peppercorns, garlic, green onion, and sesame seeds. Heat 1 tablespoon of oil until hot and pour it over the mixture to release the aroma. Add soy sauce and vinegar. Stir to combine.
Bring a pot of water to a boil. Add the wontons and stir gently to prevent sticking. Cook until the wontons float and continue boiling for another 1–2 minutes. Drain and serve hot with the dipping sauce.