Marinate the Chicken: Place the diced chicken in a bowl. Add soy sauce, cornstarch, and salt. Mix thoroughly until the chicken is well coated. Let it marinate for at least 15–20 minutes at room temperature.

Prepare the Sauce: In a small bowl, combine light soy sauce, dark soy sauce, Chinese black vinegar, hoisin sauce, sugar, sesame oil, and cornstarch slurry. Whisk until smooth. Set aside.

Toast the Chilies and Szechuan Peppercorns: Heat 1 tablespoon of oil in a wok or large skillet over medium-high heat. Add the dried chilies and Szechuan peppercorns. Stir-fry for 30 seconds or until aromatic. Remove and set aside to avoid burning during stir-frying.

Stir-Fry the Chicken: Add 2 more tablespoons of oil to the hot wok. Add the marinated chicken in a single layer. Sear for 2–3 minutes per side until golden brown and cooked through. Remove chicken and keep warm.

Sauté Aromatics and Vegetables: In the same wok, sauté garlic, ginger, and the white part of the green onions for 30 seconds. Add red and green bell peppers. Stir-fry for another 2–3 minutes until slightly tender but still crisp.

Combine Everything: Return the chicken and chilies to the wok. Stir well. Pour in the prepared Kung Pao sauce and toss to coat. Cook for 1–2 minutes until the sauce thickens and clings to the chicken.

Add Peanuts and Garnish: Stir in the roasted peanuts and green part of the green onions. Cook for another 30 seconds. Remove from heat and serve immediately.