Add the bite-size chicken pieces to a large bowl and toss with the ⅓ cup cornstarch until evenly coated.

In a bowl, combine the sesame oil, rice vinegar, low-sodium soy sauce and brown sugar. Set aside.

Heat 1 tablespoon of oil in a large skillet over medium-high heat. Add the chicken in a single layer and cook until golden brown and cooked through, turning as needed. Work in batches if necessary, adding more oil as needed. Transfer the cooked chicken to a plate.

Reduce the heat to medium-low. Add the fresh ginger and garlic to the skillet and sauté for about 1 minute, stirring constantly.

Pour the prepared sauce into the skillet and stir to combine. Allow it to simmer for a 3-5 minutes.

In a small bowl, whisk together the 1 tablespoon cornstarch and ¼ cup water until smooth. Pour the slurry into the skillet and stir.

Thicken the sauce. Cook, stirring, until the sauce thickens into a glossy consistency.

Finish the chicken. Add the cooked chicken back to the skillet and toss until evenly coated in the sauce.

Garnish. Top with the green onions and serve promptly.