Place the cauliflower florets in a large bowl of hot salted water for 3 to 4 minutes. Drain thoroughly and pat dry with paper towels.

In a mixing bowl, combine the all-purpose flour, cornstarch, ginger-garlic paste, Kashmiri red chilli powder, salt, and water. Stir until you have a smooth, thick batter that coats the back of a spoon.

Heat oil in a deep frying pan over medium-high heat. Dip each floret into the batter to coat evenly, then drop carefully into the hot oil. Fry in batches for 4 to 5 minutes until golden brown and crisp. Remove with a slotted spoon and drain on paper towels.

Heat 1 tablespoon of oil in a wok over high heat. Add the chopped garlic, ginger, green chillies, and white parts of the spring onions. Sauté for 30 seconds until aromatic.

Stir in the tomato ketchup, dark soy sauce, vinegar, and 1/4 cup of water. Pour in the cornstarch slurry and cook for 1 to 2 minutes until the sauce thickens and turns glossy.

Add the fried cauliflower florets to the wok. Toss quickly over high heat for about 1 minute until the florets are evenly coated in the sauce. Garnish with chopped green spring onion greens and serve immediately.