Prepare all ingredients before you start cooking. This dish comes together quickly, so having everything measured and sliced will help you keep up with the sizzling pan.
In a bowl, combine the chicken pieces with the cornstarch, 1 tablespoon soy sauce, and the Shaoxing wine (if using). Toss to coat evenly. Let sit 10 minutes to lightly marinate and soften the surface for a crisp sear.
In a small bowl, whisk together the remaining soy sauce, the rice vinegar, hoisin (if using), sugar, and water or stock. This will be your glossy, balanced sauce. Set aside.
Toast the Sichuan peppercorns in a dry skillet over medium heat for about 1–2 minutes until fragrant. Grind them finely using a mortar and pestle or spice grinder. This creates the signature numbing heat that defines the dish.
Heat a large skillet or wok over medium-high heat. Add the oil and swirl to coat. Add the marinated chicken in a single layer, searing undisturbed for 2–3 minutes until edges begin to color and crisp. Flip and cook another 2–3 minutes until just cooked through. Remove the chicken to a plate.
In the same pan, add a touch more oil if needed. Sauté garlic and ginger for about 30 seconds until fragrant. Add the doubanjiang and stir for another 20–30 seconds to bloom the flavors.
Return the chicken to the pan. Add the bell pepper and half of the scallions. Pour in the prepared sauce and stir to coat everything evenly. Cook for 1–2 minutes until the sauce thickens and glazes the chicken.
Finish with sesame oil, a final pinch of Sichuan pepper, and adjust with salt and pepper to taste. Remove from heat and scatter the remaining scallions over the top.
Serve immediately with steamed white rice, fried rice, or noodles. If you like extra heat, offer chili oil on the side for guests to tailor their level of spiciness.