Pat the chicken dry with paper towels, then season both sides with salt and pepper. Lightly coat with cornstarch until evenly dusted.
Heat vegetable oil in a large skillet over medium-high heat. Add chicken and cook 4–5 minutes per side until golden brown and cooked through.
While the chicken cooks, whisk soy sauce, honey, brown sugar, garlic, ginger, rice vinegar, sesame oil, and water in a bowl until smooth.
Reduce heat to medium and pour the sauce into the skillet. Let it simmer around the chicken.
Cook for 5–7 minutes, turning the chicken occasionally, until the sauce thickens and becomes glossy and sticky.
Spoon the thickened glaze over the chicken repeatedly until fully coated and caramelized.
Remove from heat once the sauce clings tightly to the chicken and slightly bubbles.
Garnish with sesame seeds and sliced green onions before serving.
