Mix the beef with egg: In a medium bowl, combine 16 oz sliced beef chuck and 1 beaten medium egg. Mix well to coat the beef evenly.

Flour the beef: Add 3 tbsp cornstarch and 1 tsp garlic powder to the beef mixture. Mix well and set aside.

Cook the beef: In a medium saucepan over medium heat, add 1 cup canola oil and wait for it to heat up. Once the oil starts to ripple, reduce the heat to low. Slowly add half of the beef to the pan, one slice at a time to avoid overlapping the pieces. Cook for 2 minutes on both sides or until golden brown. Remove from the saucepan and set aside. Continue to cook the remaining beef in the same way.

Remove excess oil: Put the cooked beef into a plate lined with paper towels to catch excess oil from the beef.

Make the sauce: In a small bowl, combine 1 tbsp brown sugar, 1 fl oz water, 1/2 tsp red pepper flakes, 1 tbsp rice vinegar, 3 1/2 tbsp ketchup, 1/2 tbsp hoisin, 1 tbsp soy sauce, 1/2 tbsp oyster sauce, and the remaining 1 tbsp cornstarch. Mix well to dissolve.

Sauté the vegetables: In a clean cast-iron skillet over medium heat, add 1/2 tbsp olive oil, 4 oz diced onion, and 2 oz diced red bell peppers. Cook for 3 minutes, stirring constantly. Transfer to a plate and set aside.

Sauté the aromatics: In the same skillet, add the remaining 1/2 tbsp olive oil, 1 tsp minced garlic, and 1 tsp minced ginger. Stir for 30 seconds over medium heat.

Combine all ingredients: To the same skillet, combine the cooked beef and sauce. Stir for 1 minute to thicken the sauce and let it coat the beef evenly.

Add the vegetables to the skillet. Cook and stir for another minute before turning the heat off.

Garnish: Sprinkle 2 tbsp scallions and 1/2 tbsp sesame seeds on top of the beef.

Serve immediately with warm cooked rice.