Prepare the sauce by whisking together the soy sauce, Worcestershire sauce, sugar, ginger and corn starch in a small bowl until smooth. Set aside.
Heat 1 ½ tablespoons (half) of the vegetable oil in a large skillet over medium high heat. Add the peppers and onions and cook for 3 to 4 minutes, or until tender crisp (stirring frequently). Add garlic and cook for an additional 30 seconds, stirring frequently.
Transfer bell pepper and garlic mixture to a plate or bowl and return skillet to burner.
Heat the remaining vegetable oil in the skillet. Add steak and cook for 5 minutes, or until browned on both sides and fully cooked (stirring frequently). Leave juices in the skillet with the steak.
Return peppers, onions and garlic to skillet with the steak and stir to combine.
Pour in the sauce and stir to coat as evenly as possible. Cook for approximately 1 to 2 minutes (while stirring), or until sauce is thickened.
Sprinkle with sesame seeds when serving, if desired.