Place the sliced beef in a bowl or a resealable plastic bag.
Pour ½ cup cornstarch into the bag and shake to coat the beef chunks.
Heat oil in a large skillet.
Pour the beef into the skillet and cook on med-high heat until the meat is seared and cooked on each side.
Once done, remove the beef and set aside.
In a small bowl, combine water, soy sauce, honey, brown sugar, rice wine vinegar, sesame oil, minced garlic, fresh ginger, and red pepper flakes and stir until honey is mostly dissolved.
In the skillet, pour some oil and sauté green onions and 1 tsp of sesame seeds for about 2 minutes.
Until slightly browned.
Add the teriyaki mixture to the skillet and cook on medium heat, stirring constantly, until thickened. About 3 minutes.
Combine the meat and teriyaki sauce and stir to make sure the beef is evenly coated.
Garnish with more sesame seeds and green onions before serving and serve over rice.