Cook the rice. Start your rice according to package directions so it’s ready when the chicken and broccoli are done.
Keep warm.
Prep the sauce. In a small bowl, whisk soy sauce, mirin (or rice vinegar), brown sugar or honey, garlic, ginger, 1/2 cup water, and sesame oil. Taste and adjust sweetness or saltiness as needed.
Make the slurry. In a separate cup, stir cornstarch with 2 tablespoons water until smooth. Set aside.
Blanch or steam the broccoli. Bring a small pot of water to a boil, add broccoli, and cook for 1–2 minutes until crisp-tender.
Drain and rinse with cold water to stop the cooking. Alternatively, steam for 2–3 minutes. Set aside.
Heat the pan. Place a large skillet or wok over medium-high heat.
Add neutral oil.
Sear the chicken. Pat chicken dry and season with a pinch of salt. Add to the hot pan in a single layer. Cook 5–7 minutes, stirring occasionally, until cooked through and lightly browned.
Avoid overcrowding; cook in batches if needed.
Add the sauce. Reduce heat to medium. Pour the teriyaki mixture over the chicken. Simmer 1–2 minutes to warm through.
Thicken. Stir the cornstarch slurry again and pour it into the pan while stirring.
Simmer 1–3 minutes until the sauce turns glossy and coats the chicken. If it gets too thick, add a splash of water.
Add broccoli. Fold in the broccoli and cook 1 minute to heat through. Add red pepper flakes or sriracha if you like heat.
Assemble bowls. Spoon rice into bowls.
Top with chicken and broccoli, making sure to get extra sauce. Garnish with sesame seeds and green onions.
Serve. Taste and adjust with a splash of soy sauce, a squeeze of lime, or a drizzle of sesame oil if desired.