In a small bowl whisk together soy sauce, brown sugar, rice vinegar, water, garlic and ginger.
Pour half of the mixture over chicken in a large bowl (or in a zip-close plastic bag) and let marinate for at least 2 hours, or preferably overnight.
Reserve the other half of the marinade to finish at cooking time.
When ready to cook the chicken, place the remaining marinade in a small pot over medium heat.
Add the cornstarch and whisk until dissolved.
Bring to a boil, reduce heat and simmer 3-4 minutes, until it just begins to thicken.
Remove from heat and set aside.
Heat a grill or cast-iron pan over high heat and cook 6-7 minutes on each side to get a nice sear.
Brush the teriyaki sauce on.
Place the chicken under a hot broiler for another 3-4 minutes on each side or until juices run clear.
Let chicken rest 10 minutes, slice into ¾-inch pieces across the grain, and serve with cabbage salad, sticky rice, and pickles, and top with green onions and sesame seeds.
