Dice the chicken breasts and place them in a bowl with the whisked egg.
Add 1 tbsp soy sauce, 1 tbsp white vinegar, salt, and black pepper. Mix until well combined.
Add 5 tbsp cornstarch to the chicken and mix until the chicken is fully coated.
Air fry the chicken at 200°C (400°F) for 12-15 minutes, or bake in the oven at 190°C (375°F) for 18-22 minutes.
In a pan, bring 150ml water to a boil. Add 30g tomato sauce, 15g brown sugar, 1 tbsp white vinegar, and 1 tbsp soy sauce.
Cook for 2 minutes, then set aside.
In the same pan, heat olive oil. Sauté the onion, green peppers, red peppers, and crushed garlic for 2 minutes.
Pour the sauce over the vegetables and stir. Mix 1 tbsp cornstarch with 50ml water and add to the pan.
Add the cooked chicken and simmer until the sauce is sticky and coats the chicken well. Sprinkle with white sesame. Serve and enjoy!