Prepare the Teriyaki Sauce: In a saucepan over medium heat, combine soy sauce, honey, rice vinegar, minced garlic, and grated ginger. Bring to a simmer. In a small bowl, mix cornstarch with water to create a slurry, then add to the saucepan. Stir until the sauce thickens. Remove from heat and set aside.

Sauté the Chicken: In a large skillet, heat sesame oil over medium-high heat. Add diced chicken and cook until browned and cooked through. Remove from heat.

Blanch the Vegetables: In a pot of boiling water, briefly cook broccoli florets, sliced carrots, and chopped red bell pepper until tender-crisp. Drain and set aside.

Assemble the Casserole: In a large mixing bowl, combine cooked rice, sautéed chicken, blanched vegetables, and frozen peas. Pour the teriyaki sauce over the mixture and stir until everything is evenly coated.

Bake: Transfer the mixture to a greased baking dish. Bake in a preheated oven at 350°F (175°C) for 20-25 minutes, until heated through and slightly golden on top.

Garnish and Serve: Remove from the oven and sprinkle with sliced green onions and sesame seeds before serving.