Cook the chicken: In a large skillet or wok, heat 1 tablespoon of oil over medium-high heat. Add the chicken and cook until browned and cooked through, about 6–8 minutes. Remove the chicken and set it aside.

Sauté the peppers: In the same skillet, add the remaining oil. Add red and yellow bell peppers and sauté for 3–4 minutes until slightly softened.

Combine with pineapple and chicken: Add the cooked chicken and pineapple chunks to the skillet with the peppers. Toss together gently.

Make the sauce: In a bowl, whisk together barbecue sauce, soy sauce, brown sugar, reserved pineapple juice, ginger, and garlic until smooth.

Simmer everything together: Pour the sauce over the chicken mixture in the skillet. Bring to a simmer and cook for 4–5 minutes, allowing flavors to meld.

Thicken the sauce: In a small bowl, mix the cornstarch with cold water to form a slurry. Pour it into the skillet while stirring continuously. Let the sauce simmer for another 2–3 minutes until thickened and glossy.

Serve: Spoon over cooked rice and top with chopped green onions and sesame seeds. Serve hot.