Prepare the chicken: Pat the chicken dry and cut it into bite-size pieces. Toss with cornstarch, salt, and black pepper.
Make the sauce: Whisk together honey, sriracha, soy sauce, rice vinegar, garlic, sesame oil, and water in a small bowl.
Brown the chicken: Heat oil in a large skillet over medium-high heat. Add chicken in a single layer and cook for 7–10 minutes, turning occasionally, until browned and cooked through.
Check the temperature: The thickest pieces should reach 165°F (74°C) on an instant-read thermometer.
Add the sauce: Reduce heat to medium-low and pour the honey sriracha sauce over the chicken. Toss well.
Glaze: Simmer for 2–4 minutes, stirring frequently, until the sauce becomes glossy and coats the chicken.
Garnish and serve: Remove from heat and sprinkle with green onions and sesame seeds. Serve hot over rice or alongside steamed vegetables.