Rinse the rice, then add the rice and water to a saucepan, bring to a boil, cover, reduce the heat to low, and let it cook for 15-18 minutes. Turn off the heat and let the rice rest for 5 to 10 minutes, covered.
In a bowl, add cubed chicken, black pepper, and onion powder. Then, toss to coat.
Heat olive oil in a large skillet over medium-high heat. Cook the chicken in a single layer, spaced apart to avoid steaming, for 5-7 minutes or until browned and the thickest pieces reach 165℉ internally. Remove, set aside, and cover with foil.
While the chicken is cooking, whisk together soy sauce, water, brown sugar, mirin, sesame oil, ginger, garlic, honey, and cornstarch in a small bowl. Set aside.
Add olive oil to the same skillet, and add broccoli and yellow squash. Saute for 5 to 7 minutes or until fork tender. Then, add cooked chicken back in.
Pour the sauce into the skillet and cook for 2-3 minutes, occasionally stirring or until it is glossy and thick enough to coat the back of a spoon.
Divide the rice among 4 bowls, top with teriyaki chicken and vegetables. Garnish with green onion and sesame seeds before serving.