In a mixing bowl, combine the pieces of chicken thigh with soy sauce, oyster sauce, black pepper, and cornstarch. Let it marinate for about 10 minutes.

In a separate bowl, whisk together the soy sauce, black vinegar, dark soy sauce, sugar, water, and cornstarch until smooth. Set aside.

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

Heat a large skillet over medium-high heat and add oil. Once hot, sauté the marinated chicken for about 8-9 minutes until browned and cooked through.

Add minced ginger, Sichuan peppercorns, dry red chili, and garlic to the pan. Sauté for 2-3 minutes until fragrant.

Add the cooked noodles and prepared sauce to the pan. Increase heat to high and toss everything together for about 2-3 minutes until the sauce thickens.

Transfer to serving plates, topping with crushed roasted peanuts and chopped green onions to enhance flavor and texture.