1. Mix all-purpose flour, cornstarch, ginger-garlic paste, black pepper, and salt in a bowl. Add water to make a smooth batter.
2. Dip cauliflower florets in the batter and deep fry until golden brown. Set aside.
3. Heat oil in a pan. Add chopped garlic and sauté until fragrant.
4. Add chopped onions and capsicum. Sauté until they turn soft.
5. Add soy sauce, tomato ketchup, chili sauce, vinegar, and sugar. Mix well.
6. Add water and bring to a boil. Add the cornstarch slurry and cook until the sauce thickens.
7. Add the fried cauliflower florets to the sauce and toss well to coat.
8. Garnish with chopped spring onions and serve hot.