In a bowl, whisk soy sauce, brown sugar (or honey), rice vinegar, sesame oil, garlic, and ginger.
Reserve ½ cup of the marinade for glazing.
Add chicken to remaining marinade, toss to coat, cover, and refrigerate at least 30 minutes (up to 8 hours).
Thread marinated chicken onto skewers, leaving space between pieces.
Preheat grill or grill pan to medium heat and lightly oil grates.
Grill skewers 10–12 minutes, turning occasionally, until chicken is cooked through and lightly charred.
Meanwhile, simmer reserved marinade with cornstarch slurry until thick and glossy.
Brush glaze over skewers during the final minutes of cooking.
Remove from heat, garnish if desired, and serve.