Heat a large pot, add a teaspoon of sesame oil and add the chicken. Once the chicken turns to white colour add 1.5 litres of water and boil over medium heat for about 15 to 25 minutes. Skim off any foam that rises to the surface.
Once the chicken is fully cooked and the broth is rich in flavour, remove the chicken pieces from the broth and set them aside. Once the chicken is cool enough to handle, shred the meat, discarding the skin and bones. Set aside the shredded chicken for the soup.
Add the soy sauce, vinegar, chilli sauce, white or black pepper powder and garlic powder. Stir to combine. Boil this for 5 minutes.
Add the sliced carrots, the white part of the spring onions and cabbage to the pot. Let it simmer for about 5-7 minutes until the vegetables are tender.
Stir in the shredded chicken, mushroom, capsicum and a teaspoon of sugar (if using). Let it simmer for another 5-7 minutes to heat through.
In a small bowl combine 4 tbsps of cornstarch with a few tablespoons of water. The liquid must be cold to prevent the cornstarch from clumping. Stir the cornstarch and water together until the mixture is completely smooth and free of lumps. It should have a consistency similar to milk.
Slowly add the cornstarch mixture to the simmering or boiling soup while stirring continuously. Continue to cook until the soup thickens, about 2-3 minutes.
Slowly drizzle the beaten eggs into the soup while gently stirring in one direction to create egg ribbons.
Adjust the seasoning with extra vinegar, chilli sauce or pepper to taste.
Serve the soup hot, garnished with sliced green onions.
Enjoy your Hot and Sour Chicken Soup!