01 - In a mixing bowl, combine soy sauce, mirin, brown sugar, honey, rice vinegar, sesame oil, minced garlic, and grated ginger. Whisk until well blended.
02 - Set aside 3 tablespoons of the marinade in a small bowl for glazing during cooking.
03 - Place chicken cubes in a large bowl or zip-top bag. Pour remaining marinade over chicken, ensuring each piece is well coated. Cover and refrigerate for at least 30 minutes, up to 2 hours.
04 - If using wooden skewers, soak them in water for 30 minutes to prevent burning during grilling.
05 - Thread marinated chicken pieces onto skewers evenly.
06 - Heat grill or broiler to medium-high heat.
07 - Grill or broil skewers for 12 to 15 minutes, rotating occasionally, until chicken is fully cooked and slightly charred at the edges.
08 - Pour reserved marinade into a small saucepan and bring to a simmer for 2–3 minutes. For a thicker glaze, stir in cornstarch mixed with a small amount of water and cook until thickened.
09 - Brush cooked skewers with the prepared teriyaki glaze for a glossy finish.
10 - Sprinkle skewers with toasted sesame seeds and sliced spring onions. Serve immediately with steamed rice or grilled vegetables if desired.