1. Make the sauce: Add all the ingredients together in a jar, shake well and set aside.
2. Prep the meat: Slice the beef into thin strips and place into a pirax dish or bowl.
3. Season the meat: Add the salt & pepper, maizena, egg, soy sauce, sesame oil, minced garlic and grated ginger. Set aside.
4. Make ahead option: Cover the meat dish with cling wrap and refrigerate from 30 minutes to overnight.
5. Cook the meat: In a wok or non stick pan, heat 2 tablespoons of oil. When the oil is hot, add the meat and cook on high heat for 3 to 4 minutes till brown. Remove and place onto a plate.

Cook the Stir-Fry the veggies

1. In the same pan, still on high heat, heat the remaining tablespoon of oil and add the onions and bell peppers and cook for 2 to 3 minutes. Shake the pan or use a spatula to scrape the bottom of the pan lifting the veggies as they cook.
2. Combine: Return the meat to the pan, give it all a mix or shake, add another half of the sauce (keep some for serving!l) and remove the pan off the heat.
3. Serve: Serve in bowls with chopsticks, chopped spring onion, toasted sesame seeds and the remaining sauce.