Start by creating a ginger-garlic-onion paste using a food processor. Blend chopped ginger, garlic, and onions until smooth. Set aside a quarter for later use.

Cut boneless chicken into 1-inch pieces and place them in a mixing bowl. Add the reserved ginger-garlic-onion paste, soy sauce, chili powder, black pepper, and a little water to marinate the chicken.

Finely dice the sweet red bell pepper and chop the reserved ginger-garlic-onion mix. Set aside for later.

Combine tomato paste, oyster sauce, dark soy sauce, rice vinegar, sugar, and water in a separate bowl. Whisk until smooth.

Coat marinated chicken pieces evenly in cornstarch before frying.

Heat oil in a pan to approximately 350°F. Fry marinated chicken in batches until golden brown and crispy, about 5 to 6 minutes.

For extra crispiness, return fried chicken to the hot oil for another 30 seconds.

Sauté the reserved ginger-garlic-onion mix in a wok over medium heat until fragrant. Add diced bell pepper and stir-fry for a minute.

Pour the prepared sauce into the wok and simmer for a few minutes until it thickens. Add the crispy fried chicken, tossing to coat.

Serve hot over rice or noodles and garnish with chopped cilantro.