Steps
1. In a small bowl, mix soy sauce, mirin, and sugar to create the teriyaki sauce.
2. In a pan, heat sesame oil over medium heat. Add the diced chicken and cook until browned and cooked through, about 5-7 minutes.
3. Pour the teriyaki sauce over the chicken and cook for an additional 2-3 minutes until the sauce thickens.
4. In the same pan, add broccoli and bell pepper, sautéing until just tender, about 3-4 minutes.
5. Serve the teriyaki chicken over a bed of cooked rice, topped with sautéed vegetables and garnished with green onions and sesame seeds.