Take chopped cabbage in a bowl. Add spring onion and salt. Mix well and leave for 15 minutes.
Remove lid and squeeze out the excess water.
Add grated carrot, chopped capsicum, salt as per taste, red chilli powder, black pepper powder, corn flour and all purpose flour. Mix well.
Prepare a soft dough. Grease your hands and make balls.
Heat oil in a kadhai/wok and fry both sides of balls on medium to high flame until they turn golden and crispy.
To prepare sauce, heat oil in a kadhai/wok at high flame.
Mix corn flour with water. Make sure there are no lumps and keep it aside.
Once the oil is heated, add chopped green chilli, ginger, garlic and saute on high flame.
After 20 seconds, add chopped onion and saute on high flame. Keep Stirring.
After 1 minute, add onion petals and capsicum and saute for 1 minute on high flame.
Add red chilli powder, black pepper powder, salt, soya sauce, vinegar, red chilli sauce, green chilli sauce, tomato ketchup and cook on low flame for a minute.
Add water as required. You can add water as you want to make it thick or light. Add corn flour slurry that was kept aside and cook on high flame.
Leave until 1 boil and turn the flame to low.
Add manchurian masala. Mix well.
Add Manchurian balls and turn off the flame.Mix well
Add spring onion. Mix well.
Serve it hot as an appetizer or with fried rice. Enjoy.