Marinate the chicken:
In a bowl, combine the chicken pieces with soy sauce, rice vinegar, cornstarch, and salt. Mix well and let it marinate for 15–20 minutes while you prepare the other ingredients.
Prepare the sauce:
In a separate bowl, whisk together soy sauce, rice vinegar, hoisin sauce, sugar, sesame oil, water, and cornstarch. Set aside.
Stir-fry the peanuts:
Heat 1 tablespoon of vegetable oil in a wok or large skillet over medium-high heat. Add the peanuts and stir-fry for 2–3 minutes until they are lightly golden and fragrant. Remove the peanuts from the pan and set them aside.
Cook the chicken:
In the same wok, add the remaining 1 tablespoon of oil. Add the marinated chicken in a single layer and stir-fry for 4–5 minutes, until it is cooked through and lightly browned. Remove the chicken from the pan and set it aside.
Stir-fry the aromatics:
In the same pan, add a little more oil if necessary. Stir-fry the garlic, ginger, and dried red chili peppers for about 1 minute, or until fragrant. If using bell peppers and onions, add them now and cook for 2–3 minutes until tender.
Combine the chicken and sauce:
Return the chicken and peanuts to the pan. Pour the prepared sauce over the ingredients and stir well to coat everything in the sauce. Cook for an additional 2–3 minutes, allowing the sauce to thicken and the chicken to absorb the flavors.
Serve:
Remove from heat and serve the Kung Pao Chicken over steamed rice. Enjoy!