01 - Soak dried wood ear mushrooms and glass noodles in warm water for 10 minutes, then 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 thoroughly by hand or spoon until all ingredients are evenly incorporated and the mixture develops a slight tackiness.
03 - Lightly grease a heatproof dish or 9x5 inch loaf pan with vegetable oil. Transfer the pork mixture to the dish and level the surface with a spatula, ensuring an even thickness for uniform cooking.
04 - Place the dish in a steamer over simmering water. Cover tightly with a lid and steam for 25-30 minutes, or until the meatloaf is firmly set and a toothpick inserted comes out clean.
05 - Beat the reserved egg yolk until smooth. After the initial 25 minutes of steaming, carefully uncover and spread the yolk evenly over the top of the meatloaf. Cover and continue steaming for an additional 5-7 minutes until the yolk layer is set and glossy.
06 - Remove the dish from the steamer and let cool for 5-10 minutes before slicing. Serve warm with jasmine rice and pickled vegetables, or use as a filling for banh mi sandwiches.