1. Marinate the Chicken: In a bowl, combine the diced chicken, soy sauce, rice vinegar, hoisin sauce, and cornstarch. Mix well and let it marinate for at least 15 minutes.
2. Prepare the Sauce: In a small bowl, mix together the chicken broth, sugar, and a bit more soy sauce if desired. Set aside.
3. Cook the Chicken: Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Add the marinated chicken and cook until it's browned and cooked through. Remove the chicken from the skillet and set aside.
4. Stir-Fry the Vegetables: In the same skillet, add the remaining tablespoon of vegetable oil. Add the dried red chilies, Sichuan peppercorns (if using), garlic, and ginger. Stir-fry for about 30 seconds until fragrant.
5. Combine Everything: Add the diced bell peppers to the skillet and stir-fry for 2-3 minutes until they start to soften. Return the cooked chicken to the skillet, along with the peanuts and green onions. Pour in the prepared sauce and stir everything together.
6. Simmer: Let the mixture simmer for a few minutes until the sauce thickens and coats the chicken and vegetables evenly.
7. Serve: Serve the Kung Pao Chicken hot with steamed rice or noodles.
