Marinate chicken with soy sauce, ginger-garlic paste, and cornstarch; fry until golden.
Sauté garlic, ginger, and green chilies in oil until fragrant.
Toss in chopped onions, capsicum, and spring onions for added crunch and flavor.
Combine soy sauce, ketchup, vinegar, and chili sauce; cook to blend the flavors.
Add cornstarch slurry (cornstarch mixed with water) to the pan, stirring until the sauce thickens.
Add the fried chicken pieces to the sauce; mix well to coat evenly.
Garnish with chopped spring onions and serve hot with fried rice or noodles.