Preheat your air fryer to 370°F (188°C).
In a bowl, mix flour, cornstarch, black pepper, salt, ginger-garlic paste, and enough water to make a thick batter.
Coat each cauliflower floret with the batter.
Arrange the coated florets in the air fryer basket. Lightly brush or spray with oil.
Air fry for 15-18 minutes, shaking halfway through, until golden and crispy.
Meanwhile, heat a pan and sauté onions, bell peppers, and green chilies until slightly soft.
Add soy sauce, ketchup, chili sauce, vinegar, and sugar. Stir well.
Toss the air-fried cauliflower into the sauce and coat evenly.
Garnish with spring onions and serve hot.