Using a medium saucepan, add soy sauce, ¼ cup water, brown sugar, honey, sesame oil, rice vinegar, garlic and ground ginger; stir until well combined. Heat, stirring occasionally, over medium-low heat until brown sugar has fully dissolved.
Using a small bowl, whisk the corn starch together with remaining ¼ cup of water; stir until well combined. Add corn starch mixture to saucepan; stir. Increase heat to medium-high and cook until glaze begins to thicken (~1-2 minutes). Stir sesame seeds into glaze.
Add fully-cooked meatballs to saucepan. Reduce heat to medium-low and stir until meatballs are well-coated. Simmer for 10-12 minutes, or until meatballs are hot.
For serving, place 4-5 meatballs over 1 cup of cooked rice. Spoon additional teriyaki glaze over meatballs and then sprinkle with chopped green onions.