Add the corn starch, salt, pepper, and egg to a large mixing bowl. Then whisk well to combine
Add the steak strips and toss to coat; this will be quite sticky
Heat 3 tbsp of the oil in a wok over high heat until very hot.
Working in at least two batches, add the beef strips one at a time, be sure to spread this out.
Fry the steak until dark brown and crisp, ~5 minutes; turn the strips after 2 minutes.
Use tongs or chopsticks to remove the beef to a plate lined with paper towels.
Add one more tbsp of oil to the pan and repeat with the rest of the beef.
Refresh the oil with up to an additional 1 tbsp of oil; use as little as possible
Add the onion and bell pepper, and cook for 2-3 minutes until tender-crisp.
Add in the finely chopped chillies, 1 tsp minced ginger, and three minced cloves of garlic, and cook whilst stirring for 30 seconds.
Add the 2 tbsp rice vinegar, 3 tbsp soy sauce, 4 tbsp sugar, 4 tbsp tomato ketchup, and the 3 tbsp sweet chilli sauce to the pan.
Turn up the heat and fast simmer until the sauce reduces slightly.
Add the beef back in, toss/stir to coat well, and heat through for 1-2 minutes – until the meat is hot.
Serve over rice or noodles, garnished with slice peppers and green onion.