**Prepare Mushrooms:** In a bowl, combine halved mushrooms with cornflour, all-purpose flour, ginger-garlic paste, and a pinch of salt. Mix well to coat the mushrooms evenly. Drizzle with 1 tbsp oil and toss again.

**Air Fry Mushrooms:** Preheat air fryer to 375°F (190°C). Arrange coated mushrooms in a single layer in the air fryer basket. Air fry for 12-15 minutes, shaking the basket halfway through, until golden brown and crispy. Set aside.

**Prepare the Sauce:** In a separate wok or pan, heat 1 tbsp cooking oil over medium-high heat. Add minced garlic, grated ginger, and slit green chilies. Sauté for 30 seconds until fragrant.

**Sauté Vegetables:** Add diced onion and bell pepper. Stir-fry on high heat for 2-3 minutes until vegetables are crisp-tender.

**Add Sauces & Seasoning:** Reduce heat to medium. Add light soy sauce, red chili sauce, tomato ketchup, white vinegar, and black pepper powder. Mix well.

**Thicken Sauce:** Pour in water or vegetable broth. Bring to a gentle simmer. Add the cornflour slurry, stirring continuously until the sauce thickens to your desired consistency.

**Combine & Garnish:** Add the air-fried mushrooms to the thickened sauce. Toss gently to coat them evenly. Cook for another 1-2 minutes, ensuring the mushrooms are well coated and heated through. Garnish with chopped spring onion greens and serve hot.