In a mixing bowl, combine the cornstarch, water, soy sauce, ground black pepper, and oysters. Mix well. Heat a skillet with some vegetable oil, add the bean sprouts, and stir-fry until just wilted. Transfer the bean sprouts to a serving plate.

Add more oil to the skillet and heat. Pour in the oyster and cornstarch mixture, then crack the eggs into the pan. Stir-fry until everything is cooked through and well combined. Place the mixture on top of the bean sprouts and sprinkle with green onions and cilantro.

For the dipping sauce, simmer all the sauce ingredients together until boiling and well combined. Let cool, then pour into a small bowl. Serve with the oyster omelet.