Begin by cutting the boneless, skinless chicken thighs or breasts into bite-sized pieces. This will ensure they cook evenly and soak up the delicious teriyaki sauce.
In a mixing bowl, combine the chicken pieces with ¾ cup of low sodium soy sauce, kosher salt, black pepper, and 2 teaspoons of cornstarch. Toss to coat the chicken evenly and let it marinate for about 10-15 minutes while you prepare the sauce.
In another bowl, whisk together the remaining 1 tablespoon of soy sauce, water, honey, rice vinegar, minced garlic, minced ginger, and red pepper flakes. This mixture will become your flavorful teriyaki sauce.
Heat the canola oil in a large skillet or wok over medium-high heat. Once hot, add the marinated chicken pieces in a single layer. Cook for about 4-5 minutes, stirring occasionally, until the chicken is browned and cooked through.
Once the chicken is cooked, pour the teriyaki sauce over it. Stir to combine. In a small bowl, mix the remaining 1 teaspoon of cornstarch with a tablespoon of water to create a slurry. Add this to the skillet and stir continuously until the sauce thickens, about 2-3 minutes.
Remove the skillet from heat and sprinkle with chopped green onions. Serve your Chicken Teriyaki over cooked brown rice and, if desired, alongside steamed stir-fry vegetables for a complete meal.