In a wok or skillet over medium heat, heat about 2- inches deep of oil to about 350 F.

In a bowl, combine chicken, ¼ teaspoon salt, ¼ teaspoon pepper, and beaten egg. Stir until well-coated.

In a wide bowl, combine cornstarch, flour, the remaining ¼ teaspoon salt and ¼ teaspoon pepper. Whisk until well distributed.

Add chicken a few pieces at a time and coat with cornstarch mixture using a fork.

Add chicken pieces to hot oil and stir gently to separate. Deep-fry for about 3 to 5 minutes or until golden brown and crisp. With a slotted spoon, remove chicken and drain on paper towels. Keep warm.

In a bowl, combine pineapple juice, sweet chili sauce, light soy sauce, and cornstarch. Stir until well-blended. Set aside.

Remove excess oil from the wok except for about 1 tablespoon. Increase heat to medium-high heat.

Add onions and bell peppers and cook, stirring frequently, for about 1 to 2 minutes or until tender yet crisp.

Add pineapples and cook for about 1 minute or until heated through. With a slotted spoon, remove from the wok and keep warm.

Stir the sweet chili sauce mixture to redistribute and add to the pan. Cook for about 30 to 40 seconds or until bubbly and thickened.

Add chicken, bell peppers, onions, and pineapples back into the pan. Gently toss to fully coat with sauce.

Transfer onto a serving platter and garnish with sesame seeds, if desired. Serve hot.