In a medium bowl, whisk together soy sauce, honey, sesame oil, mirin (or your chosen substitute), grated ginger, garlic, water, and cornstarch. Mix until the cornstarch is fully dissolved and the sauce looks smooth. Set aside while you cook the chicken.
Heat a large skillet over medium-high heat and add the oil. Once it’s hot and shimmering, add the chicken pieces in a single layer. Let them cook undisturbed for a minute to develop color, then stir and continue cooking for about 5–7 minutes, until golden and nearly cooked through.
Reduce the heat to medium-low and give the sauce another quick stir. Pour it into the pan with the chicken. Stir well to coat everything and let it simmer for 3–4 minutes, until the sauce thickens and turns glossy, clinging to each piece of chicken.
Once the chicken is fully cooked and nicely glazed, remove from heat. Top with sliced green onions and a sprinkle of white sesame seeds. Serve warm over fluffy rice, with steamed broccoli or your favorite vegetables on the side.