In a bowl whisk together all marinade ingredients. Add beef and marinade to a large zip lock bag, seal and chill at least 30 minutes (or overnight). Remove beef from zip lock bag and discard marinade. Place 2 whisked eggs in one bowl, and 1/2 cup corn starch in a second bowl. Dip the beef strips into the whisked eggs, then into the corn starch, tossing to coat well.
Heat a large pan or non stick skillet with about 2 tablespoons oil over medium heat. Discard marinade. Place 1/2 cup corn starch in a bowl and toss beef strips in the corn starch to coat. Add coated beef strips to preheated pan. Cook beef 5 minutes, stirring throughout. Add bell peppers and onions and cook an additional 3-5 minutes until beef is cooked through and crispy.
In a large sauce pan combine all sauce ingredients except for cornstarch slurry. Heat over medium heat and bring to a boil. Whisk together corn starch and water and add to boiling sauce. Stir until thickened (1-2 mins). Reduce heat. When beef is cooked through, add sauce to beef pan. Stir to coat begins and beef. Serve with rice or noodles if desired.
Notes
Spice it up: add 2 teaspoons - 1 tablespoon sriracha sauce to the sauce to give this dish a spicy kick!