In a medium saucepan, whisk together the water and cornstarch until smooth. Add the brown sugar, soy sauce, garlic powder, ginger powder, and sesame oil.

Place over medium heat and bring to a simmer, stirring often. Let it cook for 3–5 minutes, or until thickened and glossy. Set aside 1 cup of the sauce for the stir fry and keep the rest for drizzling over the bowls.

Rinse the rice in a fine mesh sieve under cool water until the water runs clear. Transfer to a medium saucepan.

Add 3 cups of water, the oil, and salt. Bring to a gentle simmer over low heat and cook until most of the water is absorbed. Stir once, then cover and let steam on very low heat for about 10 minutes. Fluff with a fork before serving.

In a bowl, toss the diced chicken with garlic powder and cornstarch until evenly coated.

Heat 1 tablespoon of oil in a large skillet or wok over medium-high heat. Add the chicken and cook for 5–7 minutes, until browned and cooked through. Transfer to a plate.

In the same pan, add the onion, bell pepper, and broccoli. Stir-fry for 4–5 minutes, or until the vegetables are crisp-tender. Return the chicken to the pan and pour in 1 cup of the reserved teriyaki sauce. Stir well to coat everything evenly and simmer for 2–3 minutes until hot and glossy.

Scoop rice into each bowl, top with the teriyaki chicken and vegetables, and drizzle with extra sauce if desired.

Garnish with sesame seeds or green onions if you like—and enjoy!