To prepare the chicken:

1. Combine the chicken with the garlic paste, salt, white pepper, red chilli flakes, and soy sauce in a bowl. Mix well after adding the egg.
2. Till a thick batter consistency is attained, gradually add the cornflour. The recipe calls for 4 tablespoons of cornstarch or flour, but you can adjust the amount to achieve the desired consistency.
3. Chicken should be marinated for 30 minutes.
4. In a shallow frying pan or wok, heat the oil for frying.
5. Chicken should be added in batches and cooked until crispy and golden brown. Maintain a low to medium heat so that the chicken will cook thoroughly from the inside out without burning.
6. Set the fried chicken aside.
7. The chicken can alternatively be oven-baked, shallow-fried

      To make the Manchurian sauce or gravy:

1. Put the tomato ketchup or tomato sauce, sriracha, soy sauce, and vinegar in a small jug or bowl. Stir, then put aside.
2. a large wok or medium-sized pot with hot oil (or Dutch oven). You can use the same pan that you used to fry the chicken; just drain the oil and leave 2 tablespoons of it in the pan.
3. Add the freshly minced garlic and entire red chilies to the heated oil. Add the chopped onions and bell pepper after one minute of sautéing.
4. Add the tomato sauce mixture that was set aside after 2 minutes of sautéing.
5. Salt, white pepper powder, red chilli flakes, and chicken stock should also be added. Add salt sparingly.
6. After allowing the mixture to boil, reduce the heat so that it is simmering.
7. The gravy will thicken and become glossy after 2 to 3 minutes of cooking the cornflour slurry.
8. Mix in the fried chicken after adding the gravy. Cook the chicken until it is thoroughly heated, about a few minutes. Due to the fried chicken batter, the gravy will thicken a little bit more. At this point, if desired, you can add extra chicken stock and adjust the spice.
9. Turn off the heat when the chicken is thoroughly heated. Serve the chicken Manchurian hot with fried rice and garnish with thinly sliced spring onions.