Make the sauce: In a bowl, whisk soy sauce, brown sugar or honey, rice vinegar, minced garlic, and ginger if using. Stir in cornstarch until smooth. Add sesame oil if you like. Taste and adjust sweetness or tang.

Marinate the chicken: Toss the chicken pieces with 2–3 tablespoons of the sauce. Let sit for 10–15 minutes while you slice the cabbage and prep garnishes.

Heat the pan: Set a large skillet or wok over medium-high heat. Add 1–2 tablespoons neutral oil and let it get hot until shimmering.

Sear the chicken: Spread chicken in a single layer. Cook without moving for 2–3 minutes to get color, then stir and cook another 3–4 minutes until almost cooked through. Transfer to a plate.

Stir-fry the cabbage: Add a bit more oil if needed. Add sliced cabbage and a pinch of salt. Cook 3–4 minutes, tossing, until it softens but stays crisp-tender. If you like spice, add red pepper flakes now.

Combine and sauce: Return chicken to the pan. Pour in the remaining sauce. Stir and cook 1–2 minutes until the sauce thickens and glosses the chicken and cabbage.

Finish and serve: Turn off the heat. Garnish with green onions and sesame seeds. Serve over hot rice or noodles.