Boil water in a big and wide pan and blanch the cauliflower florets for 5-7 minutes in boiling water.
After that, drain out the water in a colander and spread them on a tray so that extra moisture evaporated.
In a mixing bowl, add 4 tablespoon cornflour, 4 tablespoon all purpose flour, 1/2 teaspoon salt and 1/4 teaspoon pepper powder. Mix them well with a spoon. Now with the help of water, make a runny batter of it. Beat it nicely so that there are no lumps.
Add the cauliflower florets in the batter and coat them well with the batter. Now add rest 2 tablespoon cornflour and all purpose flour and mix well. This will help in florets getting a good coating.
Heat oil in a pan and drop these florets in hot oil one by one and few at a time. Deep fry them till they are light golden in colour. Take them out and keep on a kitchen towel.
Once all the florets are fried, add them again to the hot oil and fry again for few minutes till they are nice brown in colour. Take them out.
In a separate pan, heat 2 tablespoon oil over medium heat. Add chopped garlic and grated ginger and sauté. Add chopped chillies and onions to it and sauté again for 3-4 minutes. Add 3 tablespoon of spring onion greens and sauté for 2-3 minutes.
Add soy sauce, vinegar, chilli sauces, ketchup, sugar and rest of salt and pepper powder. Mix them well. Add 1/2 cup of water and let it boil. Meanwhile, mix one tablespoon of cornflour to the 1/3 cup of water. Add this to the cooking sauces and sauté till all gets boiled for few minutes.
Add cauliflower florets now and mix everything well so that florets are nicely coated. Switch off the heat.
Transfer to a serving bowl and spread the rest of spring onions on top and serve hot.