01 -
In a medium bowl, combine cornstarch and soy sauce until the cornstarch dissolves completely. Add white sugar, brown sugar, mirin, minced garlic, grated ginger, and black pepper. Mix thoroughly and set aside.
02 -
Pat the chicken thighs dry with paper towels and trim excess fat. Cover each piece with cling wrap on a cutting board and pound with a meat mallet until approximately 1/2 inch thick.
03 -
Pierce the chicken pieces with a fork to allow better marinade absorption. Place chicken in a bowl or pan and pour the marinade over it, ensuring all sides are coated. Cover and refrigerate overnight, flipping the chicken once. Store unused, clean marinade in an airtight container in the refrigerator.
04 -
Remove the chicken from the refrigerator an hour before cooking. Heat a greased grill until smoking hot. Discard used marinade and place the chicken on the grill. Cook over medium-high heat for about 5 minutes per side until fully cooked, basting occasionally if using an outdoor grill.
05 -
While the chicken is cooking, heat the remaining unused marinade in a saucepan. Boil for 1 minute while stirring until it thickens slightly. Adjust sweetness by adding sugar if desired, then set the sauce aside.
06 -
Slice the grilled chicken into strips and serve over rice, greens, or a preferred base. Drizzle the teriyaki sauce over the chicken and garnish with scallions and toasted sesame seeds if desired.