. Prepare the Chicken

Season diced chicken with salt and pepper.
Toss thoroughly in cornstarch until evenly coated.

2. Fry Until Crispy

Heat vegetable oil in a large pan or wok over medium-high heat.
Fry chicken in batches for 4–5 minutes until golden and cooked through.
Remove and place on paper towels to drain excess oil.

3. Cook the Vegetables

In the same pan (remove excess oil if needed), sauté onion and bell peppers for 3–4 minutes until slightly tender but still crisp.

4. Make the Sauce

Add ketchup, cider vinegar, brown sugar, soy sauce, grated ginger, and garlic to the pan.
Stir well.
Pour in a few tablespoons of the reserved pineapple juice to loosen the sauce and enhance flavor.

5. Combine Everything

Add pineapple pieces and cooked chicken back to the pan.
Toss everything together and simmer for 3–5 minutes until the sauce thickens and coats the chicken beautifully.

6. Serve

Serve hot over steamed rice or noodles.