Heat oil in a large skillet over medium-high heat. On a cutting board, cut chicken into 1" pieces. Add chicken and broccoli florets. Cook for 5-7 minutes, or until golden brown and cooked through, stirring occasionally. Broccoli should be tender and charred. Chicken should be fully cooked.
While Chicken and broccoli is cooking, make the rice in a rice maker or pot according to package directions. Substitue chicken broth for water for a better flavor! You can also use microwavable rice or frozen rice if needed.
While rice cooks, in a small bowl, whisk together tamari or soy sauce, brown sugar, rice vinegar, garlic, ginger, and cornstarch.
Once rice is cooked, stir in the cooked chicken and teriyaki sauce.
Add cooked white rice to the pan. Reduce heat to low, cover the pan, and cook for 5 minutes or until sauce thickens slightly.
Season with salt and pepper to taste. Garnish with sesame seeds and chopped green onions (optional) and serve immediately.