Prep:
- Marinate the chicken: Clean and pat-dry the chicken thighs. Trim off excess fat if needed, then cut into ¾-inch cubes. In a medium bowl, combine the chicken, low sodium light soy sauce, Shao Xing rice wine, kosher salt, potato starch, and sesame oil. Mix until combined well, then set aside to marinate for at least 15 minutes.
- Make the sauce: Whisk together the potato starch, white sugar, low sodium light soy sauce, Shao Xing rice wine, Chinkiang vinegar, dark soy sauce, sesame oil, and ¼ cup water in a small measuring cup (or bowl) until combined well.
- Prepare the fresh/dry ingredients: Slice/cut the garlic, ginger, spring onion white and light green parts, fresh red chilies (if using), and dried Chinese red chilies as indicated in the ingredients section, then set aside.
For the Kung Pao Chicken Stir-fry:
- Cook the chicken: Heat 2 tablespoons peanut oil in a large wok over high heat. Once hot, add the marinated chicken and immediately spread the pieces out in the wok. Cook, undisturbed for 40 seconds, then stir-fry for 1 minute or until no longer pink and the chicken is 80% cooked through. Transfer to a fine mesh strainer and hold it above the wok to let the excess oil drip into the wok. Tip the chicken pieces into a clean bowl and set aside. Wipe out the wok with paper towels.
- Stir-fry aromatics: Heat the remainder 2 tablespoons peanut oil and 1 teaspoon chili oil (if using) over high heat. Once hot, add the garlic, ginger, and spring onion white and light green parts. Stir-fry for 30 seconds until fragrant.
- Stir-fry chilies and Sichuan red peppercorns: Add the fresh red chilies, dried red chilies, and Sichuan red peppercorns. Stir-fry for 15 seconds to combine, taking care to not let the dried red chilies burn.
- Add the chicken and sauce: Give the sauce a quick stir with a spoon (the potato starch will have settled at the bottom) to loosen it up. Add the chicken back into the wok and pour the sauce on top of everything. Toss for a minute until everything is evenly coated in the sauce. If the sauce starts to get too thick, add a tablespoon of water and continue tossing to combine.
- Toss through peanuts: Add the fried peanuts and toss briefly to combine, then switch off the heat.
- To Serve: Transfer to a serving plate/dish and serve immediately with warm steamed rice.