01 - In a mixing bowl, whisk together soy sauce, mirin, brown sugar, honey, rice vinegar, sesame oil, minced garlic, and grated ginger until the sugar dissolves and the mixture is well combined.
02 - Measure out 3 tablespoons of the marinade and set aside in a small container for glazing later.
03 - Place the chicken cubes in a large bowl or zip-top bag and pour the remaining marinade over the top. Toss to coat evenly and refrigerate for at least 30 minutes, or up to 2 hours for deeper flavor.
04 - If using wooden skewers, submerge them in water for 30 minutes to prevent burning during cooking.
05 - Remove chicken from the marinade, allowing excess to drip off, and thread the pieces tightly onto skewers.
06 - Heat a grill or broiler to medium-high, ensuring the grates or rack are clean and lightly oiled.
07 - Grill or broil the skewers for 12 to 15 minutes, turning occasionally, until the chicken is cooked through and lightly charred on the edges.
08 - Pour the reserved marinade into a small saucepan and bring to a simmer over medium heat for 2 to 3 minutes. For a thicker glaze, stir in cornstarch mixed with a splash of water and cook until it coats the back of a spoon.
09 - Brush the cooked skewers generously with the teriyaki glaze. Garnish with toasted sesame seeds and sliced spring onions. Serve hot alongside steamed rice or grilled vegetables.