1Cut the boneless chicken breast into bite-sized pieces.
In a bowl, mix the chicken pieces with 1 tablespoon of soy sauce, 1 tablespoon of vinegar, and 1 tablespoon of cornflour. Let it marinate for 15-20 minutes.
Slice the large onion and bell pepper into thin strips. Finely chop the green chillies.
Heat 2 tablespoons of vegetable oil in a pan over medium-high heat.
Add the garlic paste and ginger paste to the pan and sauté for about 1 minute until fragrant.
Add the marinated chicken pieces to the pan and cook until they are golden brown and cooked through, about 5-7 minutes.
Add the sliced onion, bell pepper, and chopped green chillies to the pan. Stir-fry for another 3-4 minutes until the vegetables are slightly tender but still crisp.
Add the remaining 1 tablespoon of soy sauce, salt to taste, and 1 teaspoon of black pepper. Mix well to combine all the ingredients.
Cook for an additional 2-3 minutes, allowing the flavors to meld together.
Serve hot with steamed rice or noodles.