In a large bowl, mix together the cornstarch, flour, and salt.

Add the beaten egg, canola oil, and water, whisking until the mixture is smooth and thick like pancake batter.

Coat the chicken pieces in the batter and let them marinate for 10 minutes or up to an hour in the fridge.

Heat about one inch of vegetable oil in a medium saucepan or deep fryer to 350˚F.

Fry the battered chicken in batches for about 3-4 minutes until they are golden and crispy.

Once done, remove the chicken to a wire rack to drain excess oil.

In a skillet or wok over medium-high heat, add 1 tablespoon of oil, chopped onion, and bell peppers.

Sauté the vegetables for 2-4 minutes until they soften slightly.

Add the pineapple chunks and sauce ingredients, including minced garlic, sugar, rice vinegar, soy sauce, and ketchup, to the pan.

Allow the mixture to simmer, adjusting seasoning to taste as needed.

Mix the cornstarch and water together, then stir it into the sauce.

Let it simmer until it thickens to your desired consistency.

Return the crispy chicken to the pan and stir to coat all the pieces evenly in the sauce.

Garnish with sesame seeds if desired and serve immediately.