Dissolve the cornflour in 2 tablespoons of water and set aside. Add the pineapple juice, brown sugar, ketchup, soy sauce, and vinegar to a small pot and bring to a slow boil. Add the cornstarch mixture to the sauce and simmer for 5 minutes, or until it thickens. Reserve.
1 tablespoon cornflour, 2 tablespoons water, 1 cup pineapple juice, ½ cup brown sugar, 4 tablespoons ketchup, 4 tablespoons soy sauce, 2 tablespoons rice wine vinegar
Season the chicken pieces with salt and pepper. Mix with the cornstarch and mix until fully combined—the chicken juices should make the cornstarch wet enough to use as a base for coating with the cornflour afterwards. Coat all the pieces with the cornflour.
2 chicken breasts, Salt and pepper, ¼ cup cornstarch, ½ cup cornflour
Heat the oil at 350°F (180ºC) (if you want to test the temperature, throw a piece of bread - it should float and start softly bubbling immediately). Start frying the chicken in batches and transfer to a paper-lined sheet as soon as each piece is golden on every side.
2 cups vegetable oil
Heat a wok to medium-high. Add the vegetable oil, garlic and ginger. Cook for a couple of minutes.
2 garlic cloves, 2 tablespoons ginger, 2 tablespoons vegetable oil
Add the pineapple, peppers, and onions - sauté for a few minutes, until they start to get tender.
1 cup pineapple, ½ cup green bell pepper, ½ cup red bell pepper, ½ onion
Add the chicken and the sauce and toss to combine everything.
Serve immediately over white rice with sesame seeds and green onions.
Sesame seeds, Green onions, White rice