Heat the olive oil in a large skillet over medium-high heat until shimmering.
Add cubed chicken breasts to the skillet and cook until browned on all sides and no longer pink in the center, about 6-8 minutes.
Whisk together soy sauce, water, honey, brown sugar, rice vinegar, sesame oil (if using), ground ginger, minced garlic, and cornstarch in a medium bowl until well combined.
Pour the prepared teriyaki sauce over the cooked chicken in the skillet and stir continuously until the sauce thickens and coats the chicken nicely, approximately 3-4 minutes more on medium heat.
Remove from heat and serve immediately over steamed rice with an assortment of colorful vegetables on the side. Garnish with sesame seeds and chopped green onions.