In a small bowl, whisk together 2 tablespoons of cornstarch, 2 tablespoons of soy sauce, 2 teaspoons of oyster sauce, 1 tablespoon of rice vinegar, 1 tablespoon of chili sauce, and 1 teaspoon of sesame oil. Gradually add 1 cup of water while continuously stirring until the mixture is smooth. Set aside.
In a large mixing bowl, crack the 8 eggs and whisk them until well combined. Add salt and white pepper to taste.
To the bowl with the whisked eggs, add the bean sprouts, finely diced red bell pepper, sliced mushrooms, sliced green onions (white parts only), and minced garlic. Stir until everything is evenly coated.
Heat a frying pan or wok over medium heat and add 2 tablespoons of vegetable oil. Once the oil is hot, pour in a ladleful of the egg mixture. Cook for about 3-4 minutes on one side until the bottom is golden brown. Carefully flip the omelet and cook for another 2-3 minutes until the other side is golden and the eggs are fully cooked. Repeat with the remaining egg mixture.
Once all omelets are cooked, serve them hot drizzled with the prepared sauce. Garnish with sesame seeds and sliced green onions for an extra touch of flavor.