01 - Soak dried wood ear mushrooms and glass noodles in warm water for 10 minutes. Drain thoroughly and finely chop both ingredients.
02 - In a large mixing bowl, combine ground pork, 3 whole eggs, chopped mushrooms, glass noodles, diced onion, chopped scallions, minced garlic, fish sauce, soy sauce, sugar, black pepper, and salt. Mix by hand or with a spatula until all ingredients are evenly distributed and the mixture develops a slightly sticky texture.
03 - Lightly grease a heatproof dish or 9x5 inch loaf pan with vegetable oil. Transfer the pork mixture to the prepared dish and smooth the top surface with a spatula or the back of a spoon.
04 - Place the dish in a steamer set over simmering water. Cover tightly with a lid and steam for 25 to 30 minutes, or until the meatloaf is set and firm to the touch.
05 - Beat the remaining egg yolk in a small bowl. After the initial steaming time, carefully remove the lid and spread the beaten yolk evenly over the top of the meatloaf. Cover and steam for an additional 5 to 7 minutes, until the yolk layer is set and glossy.
06 - Remove the dish from the steamer and let the meatloaf rest for 5 to 10 minutes before slicing. Serve warm with jasmine rice and pickled vegetables, or use as a filling for banh mi sandwiches.