In a mixing bowl, combine chicken thigh with soy sauce, oyster sauce, black pepper, and cornstarch. Mix well and let sit for about 10 minutes.

Whisk together soy sauce, black vinegar, dark soy sauce, sugar, water, and cornstarch in a separate bowl until smooth.

Bring a large pot of salted water to a boil. Add the hand-cut noodles and cook for 4-5 minutes until al dente. Drain and toss with a teaspoon of oil.

Heat a skillet over medium-high heat. Add oil and then the marinated chicken. Cook for 8-9 minutes until browned and cooked through.

Add the ginger, Sichuan peppercorns, red chilies, and garlic to the pan. Stir-fry for 2-3 minutes until fragrant.

Toss in the cooked noodles and prepared sauce, stirring together over high heat for 2-3 minutes.

Plate the noodles and garnish with crushed peanuts and chopped green onions before serving.