Preheat the oven to 400°F (200°C). Lightly grease a 9x13-inch or similar glass baking dish.
In a saucepan over medium heat, combine soy sauce, brown sugar, honey, garlic, ginger, and rice vinegar. Stir until the sugar dissolves and the mixture begins to simmer.
In a small bowl, mix cornstarch and water to create a slurry. Stir it into the simmering sauce and cook for 1–2 minutes until thick and glossy. Remove from heat.
Heat oil in a skillet over medium-high heat. Add chicken pieces and cook for 4–5 minutes until lightly browned on the outside (they don’t need to be fully cooked).
Spread the cooked rice evenly in the bottom of the baking dish. Layer the chicken pieces over the rice.
Pour the teriyaki sauce evenly over the chicken, ensuring all pieces are well coated.
Bake uncovered for 20–25 minutes, or until the chicken is fully cooked and the sauce is bubbling and slightly caramelized around the edges.
Remove from the oven and let it sit for 5 minutes. Sprinkle generously with chopped green onions and optional sesame seeds.
