Heat enough vegetable oil in a large frying pan over medium heat to shallow-fry the chicken pieces.
Cut the chicken breasts into 1-inch pieces and set aside.
In a mixing bowl, whisk together the flour, garlic powder, egg, milk, salt, pepper and red chili powder until a thick batter forms.
One at a time, dip the chicken pieces into the batter to coat them evenly.
Carefully add battered chicken to the hot oil without overcrowding and fry, turning as needed, until golden brown and cooked through, about 3–5 minutes per batch depending on size.
Remove the chicken bites to a paper-towel-lined plate to drain excess oil.
Transfer the drained chicken to a serving plate and drizzle with sweet chili sauce; toss gently to coat.
Garnish with chives if desired and serve warm.