1Preheat your oven to 375°F and lightly coat a 9x13-inch baking dish with cooking spray or a thin layer of oil.
2Combine the soy sauce, honey, 1/4 cup water, rice vinegar, sesame oil, garlic, and ginger in a small saucepan. Bring the mixture to a gentle simmer over medium heat and cook.
3In a separate small bowl, whisk together the cornstarch and 2 tablespoons of water until smooth. Stir the slurry into the simmering sauce and continue cooking until the sauce thickens, then remove from heat.
4Heat a large skillet over medium heat. Add the chicken pieces and cook until browned and fully cooked.
5Add the broccoli, carrots, bell pepper, red onion, and peas to the skillet. Cook just until the vegetables begin to soften while still keeping a slight crunch.
6Stir the cooked rice into the skillet, then pour in half of the teriyaki sauce. Mix everything together until the rice, chicken, and vegetables are evenly coated.
7Transfer the mixture into the prepared baking dish and spread it into an even layer. Pour the remaining teriyaki sauce evenly over the top.
8Bake uncovered until the casserole is thoroughly heated and bubbling around the edges.
9Remove from the oven and garnish with sliced green onions and sesame seeds before serving.