In a medium bowl, whisk together the flour, cornstarch, garlic powder, onion powder, salt, pepper, and cayenne pepper (if using).
- In a separate bowl, beat the egg and add water to form a smooth batter.
- Dip each piece of chicken into the egg mixture, then coat it in the flour mixture, pressing lightly to ensure the chicken is well coated.
- Heat the vegetable oil in a large skillet or pan over medium-high heat.
- Once the oil is hot, add the chicken pieces in batches, being careful not to overcrowd the pan. Cook the chicken for about 3-4 minutes on each side or until golden brown and cooked through.
- Remove the chicken bites from the skillet and set them aside on a plate lined with paper towels to drain any excess oil.
- In the same skillet, combine the sweet chili sauce, soy sauce, rice vinegar, honey, and sesame oil (if using). Stir well and bring the mixture to a simmer.
- Add the cooked chicken bites to the sauce and toss to coat the chicken evenly in the sauce. Cook for an additional 2-3 minutes until the sauce has thickened and the chicken is well-glazed.
- Remove from heat and transfer the sweet chili chicken bites to a serving dish.
- Garnish with sesame seeds and chopped green onions before serving.