Begin by washing and patting dry the chicken breasts or thighs. Cut them into bite-sized pieces, ensuring that they are uniform for even cooking.
In a large bowl, combine the chicken pieces with garlic powder, salt, and black pepper. Toss until the chicken is evenly coated with the seasonings.
Heat 1 tablespoon of sesame oil in a large skillet over medium-high heat. Once hot, add the seasoned chicken pieces. Sauté the chicken for about 6-8 minutes or until golden brown and cooked through, stirring occasionally.
While the chicken is cooking, prepare the teriyaki sauce. In a separate mixing bowl, whisk together the soy sauce, water, brown sugar, honey, rice vinegar, minced garlic, and minced ginger until well combined.
In a small bowl, mix the cornstarch with the 2 teaspoons of cold water to create a slurry. Once the chicken is cooked, pour the teriyaki sauce over the chicken in the skillet. Stir well to combine, and then add the cornstarch slurry. Allow the sauce to simmer for 2-3 minutes until it thickens and clings to the chicken.
Remove the skillet from heat. Sprinkle the finely chopped green onions over the chicken bites for a fresh garnish. Serve your Easy Teriyaki Chicken Bites over a bed of rice or noodles, or enjoy them as is!