Prepare filling: Place a wok or stir-fry pan over high heat. Add 1 tbsp oil, swirling to coat sides. Add garlic; cook, stirring, until fragrant, about 10 seconds. Add cabbage, carrot, chives and red onion; stir fry until vegetables are tender-crisp, about 2 minutes. Add oyster-flavored sauce and sesame oil; toss to coat. Transfer vegetable mixture to a colander to drain. Set aside in a medium bowl.
Place a medium non-stick skillet over medium-high heat until hot. Add remaining 1 tsp oil, swirling to coat bottom of pan. Pour beaten egg into pan, tilting pan so egg coats bottom of pan and bottom of omelet is set, about 1 minute. Season with salt and pepper. Turn omelet over; cook until set, about 30 seconds. Slide omelet onto a cutting board. Fold in half and cut into thin shreds. Transfer to the bowl of vegetables to cool.
Form dumplings: Place one potsticker wrapper on a clean flat surface; keep remaining wrappers covered with a damp cloth to prevent them from drying out. Place one heaping tablespoon filling in center of wrapper. Moisten edges of wrapper with egg wash. Top with a second wrapper and secure edges. Starting from one end of wrapper, slightly fold over the edge (like a pie crust); continue folding around dumpling. Repeat with remaining wrappers and filling. Keep filled dumplings covered with a damp cloth to prevent from drying.
Yin dumplings: Heat 2 tbsp oil in a large nonstick skillet over medium-high heat. Add half the filled dumplings, flat side down; cook, without turning, until golden brown, about 3 minutes. Add vinegar and water; reduce heat to medium, cover and steam until dumplings are tender, about 4 minutes.
Yang dumplings: Heat remaining 2 cups oil in a wok or stir-fry pan over medium-high heat until hot. Add remaining uncooked dumplings; shallow fry, turning once, until golden brown and crisp, about 2 minutes on each side. Lift out dumplings with a slotted spoon; drain well on paper towels.
Transfer dumplings to a serving plate. Serve with soy sauce-vinegar.
Remark: For Yang dumplings, if you don’t want to shallow-fry, you can poach dumplings instead.
Chef Yan has remained an active international food ambassador throughout his career. He roams the world representing different commercial and social concerns to entertain and educate the public, sharing with them his unique humor and strong passion for Chinese cooking.