In a medium bowl, whisk together soy sauce, mirin, brown sugar, honey, garlic, ginger, rice vinegar, and sesame oil

Reserve 1/4 cup of the marinade in a separate bowl for basting later

Add chicken pieces to the remaining marinade, toss to coat, and refrigerate for at least 30 minutes (up to 4 hours)

If using wooden skewers, soak them in water for 30 minutes to prevent burning

Thread marinated chicken pieces onto skewers, alternating with bell pepper and onion if using

Discard used marinade that the raw chicken was in

Preheat grill or grill pan to medium-high heat

Grill skewers for 4-5 minutes per side, until chicken is cooked through and has nice grill marks

While cooking, baste with reserved marinade during the last few minutes of cooking

In a small saucepan, combine the reserved marinade with cornstarch and water

Bring to a simmer over medium heat, stirring constantly until thickened into a glaze (about 2-3 minutes)

Remove skewers from grill and brush with the teriyaki glaze

Serve over jasmine rice, garnished with green onions and sesame seeds